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物种起源|The Origin of Species

第一章　驯化变异|CHAPTER I　VARIATION UNDER DOMESTICATION

属类： 双语小说 【分类】其他读物 阅读：[12178]
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变异性的原因——习性的效果——相关生长——遗传——家养变种的性状——难以区别变种和物种——来自一个以上物种的家养变种起源——各种家鸽，差异和起源——古代依据的选择原理及其效果——有计划选择和无意识选择——家养产品的未知起源——有利于人工选择的情况

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Causes of Variability—Effects of Habit—Correlation of Growth—Inheritance—Character of Domestic Varieties—Difficulty of distinguishing between Varieties and Species—Origin of Domestic Varieties from one or more Species—Domestic Pigeons, their Differences and Origin—Principle of Selection anciently followed, its Effects—Methodical and Unconscious Selection—Unknown Origin of our Domestic Productions—Circumstances favourable to Man’s power of Selection

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对于古老的栽培植物和驯养动物来说，我们观察其同一变种或亚变种时，最先注意到的要点之一，便是个体差异一般远比自然状况下的任何物种或变种来得大。栽培植物和驯养动物品种繁多，古往今来在千差万别的气候和待遇下发生了变异，我们只消对此加以思索，势必得出结论：这种巨大的变异性，是由于家养生物所处的生活条件，不像亲种在自然状况下的生活条件那么千篇一律，而是有所不同。依我看，奈特（Andrew Knight）提出的观点亦有一定的可能性；他认为这种变异性也许在某种程度上与食料过量相关。似乎很明显，生物必须在新条件下生长数世代才能发生任何可察觉变异；并且，生物体制一旦开始变异，一般能够继续变异许多世代。能变异的有机体在培育下停止变异的个案，尚未见于记载。最古老的栽培植物，例如小麦，至今还在经常性地产生新变种；最古老的驯养动物，至今还能迅速地改良或变异。

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When we look to the individuals of the same variety or sub-variety of our older cultivated plants and animals, one of the first points which strikes us, is, that they generally differ much more from each other, than do the individuals of any one species or variety in a state of nature. When we reflect on the vast diversity of the plants and animals which have been cultivated, and which have varied during all ages under the most different climates and treatment, I think we are driven to conclude that this greater variability is simply due to our domestic productions having been raised under conditions of life not so uniform as, and somewhat different from, those to which the parent-species have been exposed under nature. There is, also, I think, some probability in the view propounded by Andrew Knight, that this variability may be partly connected with excess of food. It seems pretty clear that organic beings must be exposed during several generations to the new conditions of life to cause any appreciable amount of variation; and that when the organisation has once begun to vary, it generally continues to vary for many generations. No case is on record of a variable being ceasing to be variable under cultivation. Our oldest cultivated plants, such as wheat, still often yield new varieties: our oldest domesticated animals are still capable of rapid improvement or modification.

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无论何种原因的变异性，一般是在生命的什么阶段发生作用的，是胚胎发育的前期还是后期，还是在受孕的时刻，这一直有争论。乔弗罗伊·圣提雷尔（Geoffroy St. Hilaire）的实验结果表明，胚胎的不自然处理可致畸，而畸形与普通的变异没有任何清晰的界线分开。可是我强烈怀疑，变异性的最常见原因，可能归结于雌雄生殖质在受孕之前就受到了影响。我这么认为，原因有若干。而主要原因是圈养或者栽培对于生殖系统功能的影响非同小可；面对生活条件的任何变化，生殖系统似乎远比任何其他器官易感得多。驯养动物易如反掌，而要让圈养的动物自由生育，即使雌雄交配的个案不少，也是难上加难。有多少动物，即使在原产地松散圈养，长期生活，也不能生育！人们一般把这种情形归因于本能受损，但许多栽培植物表现得极其茁壮，却极少结实，或从不结实！已经在少数这种个案中发现，很微小的变化，如在某一个生长期内，水分多些或少些，便能决定植物是否结实。关于这个奇怪的问题，我所搜集的细节洋洋洒洒，无法在此详述。要说明决定圈养动物生殖的法则是多么奇妙，我只需提及食肉动物，即使是从热带来的，也能颇为自由地在英国圈养中生育，只有跖行动物即熊科动物例外；然而食肉鸟，除极少数例外，几乎都不会产下受精卵。许多外来的植物，花粉完全不中用，情况同最不能生育的杂种一模一样。一方面，我们看到多种家养的动植物，虽然常常体弱多病，却能在圈养中自由生育；另一方面，我们看到一些个体虽然自幼就被从自然界中抓来，已经完全驯化，而且长命和强健（关于这点，我可以举出无数事例），然而生殖系统由于未知原因而受到了严重影响，以致失去作用；那么，即使生殖系统在圈养中发生作用，其作用不规则，并且所生的后代同双亲不全相像，或者有变异性，就不足为奇了。

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It has been disputed at what period of life the causes of variability, whatever they may be, generally act; whether during the early or late period of development of the embryo, or at the instant of conception. Geoffroy St. Hilaire’s experiments show that unnatural treatment of the embryo causes monstrosities; and monstrosities cannot be separated by any clear line of distinction from mere variations. But I am strongly inclined to suspect that the most frequent cause of variability may be attributed to the male and female reproductive elements having been affected prior to the act of conception. Several reasons make me believe in this; but the chief one is the remarkable effect which confinement or cultivation has on the functions of the reproductive system; this system appearing to be far more susceptible than any other part of the organisation, to the action of any change in the conditions of life. Nothing is more easy than to tame an animal, and few things more difficult than to get it to breed freely under confinement, even in the many cases when the male and female unite. How many animals there are which will not breed, though living long under not very close confinement in their native country! This is generally attributed to vitiated instincts; but how many cultivated plants display the utmost vigour, and yet rarely or never seed! In some few such cases it has been found out that very trifling changes, such as a little more or less water at some particular period of growth, will determine whether or not the plant sets a seed. I cannot here enter on the copious details which I have collected on this curious subject; but to show how singular the laws are which determine the reproduction of animals under confinement, I may just mention that carnivorous animals, even from the tropics, breed in this country pretty freely under confinement, with the exception of the plantigrades or bear family; whereas, carnivorous birds, with the rarest exceptions, hardly ever lay fertile eggs. Many exotic plants have pollen utterly worthless, in the same exact condition as in the most sterile hybrids. When, on the one hand, we see domesticated animals and plants, though often weak and sickly, yet breeding quite freely under confinement; and when, on the other hand, we see individuals, though taken young from a state of nature, perfectly tamed, long-lived, and healthy (of which I could give numerous instances), yet having their reproductive system so seriously affected by unperceived causes as to fail in acting, we need not be surprised at this system, when it does act under confinement, acting not quite regularly, and producing offspring not perfectly like their parents or variable.

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都说不育性是园艺学的毒药，但我们依同理将变异性归咎于产生不育性的同样原因，而变异性是园艺中所有精品的来源。我还要补充一下，正如有些生物能够在最不自然的条件下（例如养在箱内的兔及貂）自由生育，这表明其生殖系统未受损，有些动物和植物也能够经受住家养或栽培，而且变化轻微，不亚于在自然状况下。

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sterility has been said to be the bane of horticulture; but on this view we owe variability to the same cause which produces sterility; and variability is the source of all the choicest productions of the garden. I may add, that as some organisms will breed most freely under the most unnatural conditions (for instance, the rabbit and ferret kept in hutches), showing that their reproductive system has not been thus affected; so will some animals and plants withstand domestication or cultivation, and vary very slightly—perhaps hardly more than in a state of nature.

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关于“芽变植物”（sporting plants），可以随便列成一个长表。这个园艺术语指的是，植株会突然生出一个芽，与同株的其他芽不同，具有新的有时是显著不同的性状。可用嫁接等方法来繁殖这种芽，有时候也可用种子。这种“芽变”自然状况下极少见，但栽培状况下则不罕见。在这个个案中，我们看到处理亲本影响了一个枝芽，而不是胚珠或者花粉。但大多数生理学者认为，芽和胚珠在最初形成阶段并无本质区别，所以实际上，“芽变”支持我的观点，即变异性大致可以归结于受精动作之前亲本处理对于胚珠或者花粉影响，或者两者兼而有之。反正这些个案表明，变异不一定如某些作者假设的那样与生殖动作相关。

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A long list could easily be given of “sporting plants;” by this term gardeners mean a single bud or offset, which suddenly assumes a new and sometimes very different character from that of the rest of the plant. Such buds can be propagated by grafting, etc., and sometimes by seed. These “sports” are extremely rare under nature, but far from rare under cultivation; and in this case we see that the treatment of the parent has affected a bud or offset, and not the ovules or pollen. But it is the opinion of most physiologists that there is no essential difference between a bud and an ovule in their earliest stages of formation; so that, in fact, “sports” support my view, that variability may be largely attributed to the ovules or pollen, or to both, having been affected by the treatment of the parent prior to the act of conception. These cases anyhow show that variation is not necessarily connected, as some authors have supposed, with the act of generation.

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同一水果的幼苗，同胎中的幼体，有时彼此大不相同，尽管米勒说过，幼体与亲本显然处于毫无二致的生活条件之中。这表明生活条件的直接影响相对于繁殖定律、生长定律、遗传定律来说是多么的微不足道。如果条件的作用是直接的，那么任何幼体一出现变异，全体也许会以同样方式变异的。对于任何变异，我们很难判断在多大程度上归结于热量、水分、光线、食物等等直接动作。我的印象是，对于动物，这种力量产生的直接影响微乎其微，但对于植物看起来影响要大一些。根据这一观点，巴克曼（Buckman）先生最近对植物做的实验似乎极有价值。当处于某种条件下的所有或者几乎所有个体受到同样方式的影响，乍一看变化似乎是直接受到这种条件的影响，但有时候可以说明，相反的条件会产生类似的结构变化。不过，依我看，少许的轻微变化可以归结为生活条件的直接影响，比如增加食量有时候就扩大了个头，某种食物能产生色彩，光线能产生色彩，气候变化也许能使皮毛增厚。

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Seedlings from the same fruit, and the young of the same litter, sometimes differ considerably from each other, though both the young and the parents, as Müller has remarked, have apparently been exposed to exactly the same conditions of life; and this shows how unimportant the direct effects of the conditions of life are in comparison with the laws of reproduction, and of growth, and of inheritance; for had the action of the conditions been direct, if any of the young had varied, all would probably have varied in the same manner. To judge how much, in the case of any variation, we should attribute to the direct action of heat, moisture, light, food, etc., is most difficult: my impression is, that with animals such agencies have produced very little direct effect, though apparently more in the case of plants. Under this point of view, Mr. Buckman’s recent experiments on plants seem extremely valuable. When all or nearly all the individuals exposed to certain conditions are affected in the same way, the change at first appears to be directly due to such conditions; but in some cases it can be shown that quite opposite conditions produce similar changes of structure. Nevertheless some slight amount of change may, I think, be attributed to the direct action of the conditions of life—as, in some cases, increased size from amount of food, colour from particular kinds of food and from light, and perhaps the thickness of fur from climate.

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习性也具有决定性的影响，如植物从一种气候移植到另一种气候，就可影响开花期。动物则有更显著的影响，例如我发现家鸭的翅骨与整体骨骼的比重比野鸭轻，腿骨却比野鸭的腿骨重。我看这种变化可以稳妥地归结于家鸭比其野生的祖先少飞多走。奶牛和奶山羊的乳房，在惯于挤奶的国家就比其他地方发育得更大，而这种发育是遗传的，这是使用产生影响的另一例子。在某些国家，所有家养动物的耳朵都是下垂的，有人认为耳朵的下垂是由于动物很少受危险惊吓而耳朵肌肉不使用的缘故，这种观点似乎有道理。

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Habit also has a decided influence, as in the period of flowering with plants when transported from one climate to another. In animals it has a more marked effect; for instance, I find in the domestic duck that the bones of the wing weigh less and the bones of the leg more, in proportion to the whole skeleton, than do the same bones in the wild-duck; and I presume that this change may be safely attributed to the domestic duck flying much less, and walking more, than its wild parent. The great and inherited development of the udders in cows and goats in countries where they are habitually milked, in comparison with the state of these organs in other countries, is another instance of the effect of use. Not a single domestic animal can be named which has not in some country drooping ears; and the view suggested by some authors, that the drooping is due to the disuse of the muscles of the ear, from the animals not being much alarmed by danger, seems probable.

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许多法则支配着变异，少数几条依稀可见，容后略加讨论。这里只打算提一下所谓的相关生长现象。胚胎或幼虫发生任何变化，几乎肯定会引起成熟动物也发生变化。畸形生物身上不同部位之间的相关性是很奇怪的；关于这个问题，圣提雷尔的大作里记载了许多事例。饲养者们相信，四肢长几乎都伴随着长脑袋。有些相关的例子十分奇怪，例如蓝眼睛的猫一般都耳聋。体色和体质特性的关联，在动植物中都有许多显著的例子。据霍依兴格（Heusinger）所搜集的事实来看，白毛绵羊和白毛猪吃了某些有毒植物会受到损害，而深色毛的个体则不会。无毛的狗，牙齿不全；长毛和粗毛的动物，据说易于出长角或多角；毛脚的鸽，外趾间有皮；短嘴的鸽，脚小；长嘴的鸽，脚大。因此，人如果继续选择任何特性，就此加强它，那么由于神秘的相关生长法则，几乎肯定会在无意中改变身体结构的其他部位。

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There are many laws regulating variation, some few of which can be dimly seen, and will be hereafter briefly mentioned. I will here only allude to what may be called correlation of growth. Any change in the embryo or larva will almost certainly entail changes in the mature animal. In monstrosities, the correlations between quite distinct parts are very curious; and many instances are given in Isidore Geoffroy St. Hilaire’s great work on this subject. Breeders believe that long limbs are almost always accompanied by an elongated head. Some instances of correlation are quite whimsical; thus cats with blue eyes are invariably deaf; colour and constitutional peculiarities go together, of which many remarkable cases could be given amongst animals and plants. From the facts collected by Heusinger, it appears that white sheep and pigs are differently affected from coloured individuals by certain vegetable poisons. Hairless dogs have imperfect teeth; long-haired and coarse-haired animals are apt to have, as is asserted, long or many horns; pigeons with feathered feet have skin between their outer toes; pigeons with short beaks have small feet, and those with long beaks large feet. Hence, if man goes on selecting, and thus augmenting, any peculiarity, he will almost certainly unconsciously modify other parts of the structure, owing to the mysterious laws of the correlation of growth.

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未知的或仅依稀可见的各种变异法则，造成了极其复杂，多种多样的结果。关于几种古老的栽培植物如风信子（hyacinth）、马铃薯，甚至大理花等的若干论文，非常值得细读；看到变种和亚变种之间在构造和体质的无数点上的彼此轻微差异，的确令人感到惊奇。生物的全部体制似乎变成可塑的了，倾向于很轻微地偏离其亲类型的体制。

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The result of the various, quite unknown, or dimly seen laws of variation is infinitely complex and diversified. It is well worth while carefully to study the several treatises published on some of our old cultivated plants, as on the hyacinth, potato, even the dahlia, etc.; and it is really surprising to note the endless points in structure and constitution in which the varieties and sub-varieties differ slightly from each other. The whole organisation seems to have become plastic, and tends to depart in some small degree from that of the parental type.

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凡是不遗传的变异，与我们无关。但是能遗传的构造上的偏差，不论在生理上是轻微的，还是重要的，其数量和多样性是无限的。卢卡斯博士（Prosper Lucas）的两大卷论文，是关于这个问题的最充实最优秀的著作。没有一个饲养者怀疑，遗传倾向有多么的强；类生类（Like produces like）是基本的信念：只有空谈理论的人才对这个原理有所怀疑。当偏差层出不穷，并且均见于父与子，我们说不清这是否由于同一原因作用于二者的结果。但是，在显然处于同样条件下的个体中间，由于环境条件的异常组合，而亲代出现任何很罕见的偏差（比如在数百万个体中，偶然出现一个），并且又重现于子代，那么我们光凭机缘说就几乎不得不把重现归结于遗传。大家想必都听说过白化病、皮肤刺痛及身上多毛等出现在同一家庭中几个成员身上的情况。如果奇异而稀少的构造偏差确是遗传的，那么不大奇异的普通偏差，当然也可以认为是遗传的了。把各种性状的遗传看作规律，把不遗传看作异常，大概是看待整个问题的正道。

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Any variation which is not inherited is unimportant for us. But the number and diversity of inheritable deviations of structure, both those of slight and those of considerable physiological importance, is endless. Dr. Prosper Lucas’s treatise, in two large volumes, is the fullest and the best on this subject. No breeder doubts how strong is the tendency to inheritance: like produces like is his fundamental belief: doubts have been thrown on this principle by theoretical writers alone. When a deviation appears not unfrequently, and we see it in the father and child, we cannot tell whether it may not be due to the same original cause acting on both; but when amongst individuals, apparently exposed to the same conditions, any very rare deviation, due to some extraordinary combination of circumstances, appears in the parent—say, once amongst several million individuals—and it reappears in the child, the mere doctrine of chances almost compels us to attribute its reappearance to inheritance. Every one must have heard of cases of albinism, prickly skin, hairy bodies, etc., appearing in several members of the same family. If strange and rare deviations of structure are truly inherited, less strange and commoner deviations may be freely admitted to be inheritable. Perhaps the correct way of viewing the whole subject, would be, to look at the inheritance of every character whatever as the rule, and non-inheritance as the anomaly.

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支配遗传的法则是未知的。没有人能说清，同种的不同个体间或者异种个体间，同一特性为什么有时候遗传有时候不遗传；为什么子代常常返回去重现祖父母的某些性状，或者重现更远祖先的性状；为什么一种特性常常从一性传给雌雄两性，或只传给一性，比较普通的是传给同性，但并不排他。出现于雄性家畜的特性，常常排他地或者更多地传给雄性，这对我们是颇为重要的事实。有一个更重要的规律，我想是可靠的，即一种特性不管在哪个年龄段初次出现，就倾向于在相当的年龄在后代身上重现，虽然有时候会提早一些。在许多个案中，这绝无例外。例如，牛角的遗传特性，仅在其后代将近成熟时才会出现；而蚕的各种特性，在相应的幼虫期或茧期中出现。但是，遗传病以及其他一些事实，使我相信，这种规律适用于更大的范围，即一种特性虽然没有明显的理由应该在一定年龄出现，可是它在后代身上出现时，偏偏倾向于在父代初次出现的同一时期。我认为，这一规律对解释胚胎学的法则是极其重要的。这些话当然是专指特性的初次出现，而并非指可能作用于胚珠或雄性生殖质的主因而言；同理，短角母牛和长角公牛杂交后，其后代的角变长了，虽然长大了才出现，但显然是由于雄性生殖质的作用。

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The laws governing inheritance are quite unknown; no one can say why the same peculiarity in different individuals of the same species, and in individuals of different species, is sometimes inherited and sometimes not so; why the child often reverts in certain characters to its grandfather or grandmother or other much more remote ancestor; why a peculiarity is often transmitted from one sex to both sexes, or to one sex alone, more commonly but not exclusively to the like sex. It is a fact of some little importance to us, that peculiarities appearing in the males of our domestic breeds are often transmitted either exclusively, or in a much greater degree, to males alone. A much more important rule, which I think may be trusted, is that, at whatever period of life a peculiarity first appears, it tends to appear in the offspring at a corresponding age, though sometimes earlier. In many cases this could not be otherwise: thus the inherited peculiarities in the horns of cattle could appear only in the offspring when nearly mature; peculiarities in the silkworm are known to appear at the corresponding caterpillar or cocoon stage. But hereditary diseases and some other facts make me believe that the rule has a wider extension, and that when there is no apparent reason why a peculiarity should appear at any particular age, yet that it does tend to appear in the offspring at the same period at which it first appeared in the parent. I believe this rule to be of the highest importance in explaining the laws of embryology. These remarks are of course confined to the first appearance of the peculiarity, and not to its primary cause, which may have acted on the ovules or male element; in nearly the same manner as in the crossed offspring from a short-horned cow by a long-horned bull, the greater length of horn, though appearing late in life, is clearly due to the male element.

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提起返祖问题，不妨说一说学者们时常提出的论点——家养变种放归到野生状态，就逐渐地但必然地要回归原始祖先的性状。所以，有人曾经说，不能从家养种族以演绎法来推论自然状况下的物种。我曾努力探求，人们是根据什么决定性事实而如此频繁地、大胆地提出上一论点的，但无功而返。要证明它的正确性是很困难的：我们可以稳妥地断言，绝大多数特征显著的家养变种无法在野生状况下生活。许多情况下，我们不知道原始祖先究竟是什么，也就说不清所发生的返祖现象是否近乎完全。为了防止杂交的影响，大概有必要只把单独一个变种放养在它的新家乡。不过，由于变种有时候的确会重现祖代类型的某些性状，所以我觉得这是不无可能的：如果我们能成功地在许多世代里使诸如圆白菜（cabbage）的若干族在极瘠薄土壤上（但在这种情形下，有些影响应归因于瘠土的直接作用）归化或进行栽培，它们大都甚至全部都会回归野生原始祖先的性状。实验能否成功，对于我们的论点并不十分重要；因为实验本身就改变了生活条件。如果能证明家养变种，如果圈养条件不变，如果大群圈养使之自由杂交，通过相互混合遏制构造上任何轻微的偏差，而仍然显示强劲的返祖倾向——即失去它们的获得性状，那么我会同意，不能从家养变种来推论有关物种的事情。但是有利于这种观点的证据毫无踪迹：要断定我们不能使驭马赛马、长角牛和短角牛、各品种鸡、各种日常蔬菜无数世代地繁殖下去，是违反一切经验的。还可以补充一句，自然状态下生活条件真的有变化时，也许会发生性状的变异和返祖；不过，下一章将说明，自然选择将决定这样出现的新性状可保留多久。

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Having alluded to the subject of reversion, I may here refer to a statement often made by naturalists—namely, that our domestic varieties, when run wild, gradually but certainly revert in character to their aboriginal stocks. Hence it has been argued that no deductions can be drawn from domestic races to species in a state of nature. I have in vain endeavoured to discover on what decisive facts the above statement has so often and so boldly been made. There would be great difficulty in proving its truth: we may safely conclude that very many of the most strongly-marked domestic varieties could not possibly live in a wild state. In many cases we do not know what the aboriginal stock was, and so could not tell whether or not nearly perfect reversion had ensued. It would be quite necessary, in order to prevent the effects of intercrossing, that only a single variety should be turned loose in its new home. Nevertheless, as our varieties certainly do occasionally revert in some of their characters to ancestral forms, it seems to me not improbable, that if we could succeed in naturalising, or were to cultivate, during many generations, the several races, for instance, of the cabbage, in very poor soil (in which case, however, some effect would have to be attributed to the direct action of the poor soil), that they would to a large extent, or even wholly, revert to the wild aboriginal stock. Whether or not the experiment would succeed, is not of great importance for our line of argument; for by the experiment itself the conditions of life are changed. If it could be shown that our domestic varieties manifested a strong tendency to reversion,—that is, to lose their acquired characters, whilst kept under unchanged conditions, and whilst kept in a considerable body, so that free intercrossing might check, by blending together, any slight deviations of structure, in such case, I grant that we could deduce nothing from domestic varieties in regard to species. But there is not a shadow of evidence in favour of this view: to assert that we could not breed our cart and race-horses, long and short-horned cattle, and poultry of various breeds, and esculent vegetables, for an almost infinite number of generations, would be opposed to all experience. I may add, that when under nature the conditions of life do change, variations and reversions of character probably do occur; but natural selection, as will hereafter be explained, will determine how far the new characters thus arising shall be preserved.

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当我们观察家养动物和栽培植物的遗传变种，即种族，并且把它们同亲缘近似的物种相比较时，如上所述，我们一般会觉察出各个家养族在性状上不如真种（true species）千篇一律。另外，同一物种的家养族的性状往往略带畸形；我是说，它们彼此之间，和同属的其他物种之间，虽然在若干方面大同小异，但是，当它们互相比较，尤其是同自然状况下亲缘最近的所有物种相比较，往往身体的某一部分有极端的差异。除了畸形性状（还有变种杂交的完全能育性——这一问题容后讨论）之外，同种的家养族的彼此差异，和自然状况下同属的亲缘近似物种差异方式相同，只是大多数情况下差异更小而已。我想，必须承认这一点，因为动植物的家养族中，没有一种不曾被某些能干的鉴定家划作区区变种，同时被另一些能干的鉴定家划作原来不同的物种的后代。如果一个家养族和物种之间存在着显著区别，这个怀疑的源泉便不致如此旷日持久地反复出现了。常有人说，家养族之间的性状差异不具有属别价值。我看可以阐明这种说法是不正确的；但学者们确定究竟什么性状才具有属别价值时，意见千差万别；这种评价目前都是凭经验取得的。而且，根据我下面提出的属别起源，我们无权期望在家养族中常常遇到属别差异。

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When we look to the hereditary varieties or races of our domestic animals and plants, and compare them with species closely allied together, we generally perceive in each domestic race, as already remarked, less uniformity of character than in true species. Domestic races of the same species, also, often have a somewhat monstrous character; by which I mean, that, although differing from each other, and from the other species of the same genus, in several trifling respects, they often differ in an extreme degree in some one part, both when compared one with another, and more especially when compared with all the species in nature to which they are nearest allied. With these exceptions (and with that of the perfect fertility of varieties when crossed,—a subject hereafter to be discussed), domestic races of the same species differ from each other in the same manner as, only in most cases in a lesser degree than, do closely-allied species of the same genus in a state of nature. I think this must be admitted, when we find that there are hardly any domestic races, either amongst animals or plants, which have not been ranked by some competent judges as mere varieties, and by other competent judges as the descendants of aboriginally distinct species. If any marked distinction existed between domestic races and species, this source of doubt could not so perpetually recur. It has often been stated that domestic races do not differ from each other in characters of generic value. I think it could be shown that this statement is hardly correct; but naturalists differ most widely in determining what characters are of generic value; all such valuations being at present empirical. Moreover, on the view of the origin of genera which I shall presently give, we have no right to expect often to meet with generic differences in our domesticated productions.

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估计同种的家养族之间的构造差异量时，我们会很快陷入疑团，不知道它们究竟是从一个或几个亲种传下来的。这一点如果能澄清，倒是很有趣的。例如，阐明众所周知纯种繁殖后代的长驱跑狗（greyhound）、嗅血警犬（bloodhound）、（terrier）、长耳猎狗（spaniel）和斗牛狗（bulldog）都是某一物种的后代，就很有分量，使我们怀疑栖息在世界各地的许多密切近似的自然种（例如许多狐类）的不变性。我并不相信狗类是从一个野生亲种传下来的，这一点后面就要讲到；但是，关于其他某些家养物种的族，却有推定的，甚至有力的证据支持这种观点。

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When we attempt to estimate the amount of structural difference between the domestic races of the same species, we are soon involved in doubt, from not knowing whether they have descended from one or several parent-species. This point, if it could be cleared up, would be interesting; if, for instance, it could be shown that the greyhound, bloodhound, terrier, spaniel, and bull-dog, which we all know propagate their kind so truly, were the offspring of any single species, then such facts would have great weight in making us doubt about the immutability of the many very closely allied and natural species—for instance, of the many foxes—inhabiting different quarters of the world. I do not believe, as we shall presently see, that all our dogs have descended from any one wild species; but, in the case of some other domestic races, there is presumptive, or even strong, evidence in favour of this view.

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常常有人设想，人类选择拿来家养的动植物，都具有非凡的内在变异倾向，也都易于经受住各种气候。这些容纳能力大大地增加了大多数家养生物的价值，对此我并不争辩。但是，未开化人最初驯养一种动物时，怎么知道是否会在连续世代中发生变异，并且经受住别种气候呢？驴和珍珠鸡的变异性弱，驯鹿的耐热力小，普通骆驼的耐寒力小，难道这阻碍它们被家养了吗？我不能怀疑，若从自然状态中取来其他一些动植物，其数目、产地及分类纲目都相等于我们的家养生物，让其在家养状况下繁殖同样多的世代，那么它们平均发生的变异，会像现存家养生物的亲种一样多。

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It has often been assumed that man has chosen for domestication animals and plants having an extraordinary inherent tendency to vary, and likewise to withstand diverse climates. I do not dispute that these capacities have added largely to the value of most of our domesticated productions; but how could a savage possibly know, when he first tamed an animal, whether it would vary in succeeding generations, and whether it would endure other climates? Has the little variability of the ass or guinea-fowl, or the small power of endurance of warmth by the rein-deer, or of cold by the common camel, prevented their domestication? I cannot doubt that if other animals and plants, equal in number to our domesticated productions, and belonging to equally diverse classes and countries, were taken from a state of nature, and could be made to breed for an equal number of generations under domestication, they would vary on an average as largely as the parent species of our existing domesticated productions have varied.

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至于大多数自古驯化的动植物，究竟是一个还是多个野生物种传下来的，我看不可能得到定论。驯养动物多源论的主要论点是，在上古记载中，特别是埃及石碑上，发现的家畜品种繁多，而其中有些品种与现存的种类大同小异。哪怕这一点证明属实，不折不扣，普遍适用，我也不以为然，除了某些品种在那里原产，有四五千年历史了，它又能说明什么呢？然而，霍纳（Horner）先生的研究证明，一万三四千年前，尼罗河谷存在开化到了制陶的人类是有一定的可能性的；谁会冒昧声称，在这个古代之前多少年，埃及就不存在拥有半驯化狼狗的野人，就像火地岛、澳大利亚的野人？

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In the case of most of our anciently domesticated animals and plants, I do not think it is possible to come to any definite conclusion, whether they have descended from one or several species. The argument mainly relied on by those who believe in the multiple origin of our domestic animals is, that we find in the most ancient records, more especially on the monuments of Egypt, much diversity in the breeds; and that some of the breeds closely resemble, perhaps are identical with, those still existing. Even if this latter fact were found more strictly and generally true than seems to me to be the case, what does it show, but that some of our breeds originated there, four or five thousand years ago? But Mr. Horner’s researches have rendered it in some degree probable that man sufficiently civilized to have manufactured pottery existed in the valley of the Nile thirteen or fourteen thousand years ago; and who will pretend to say how long before these ancient periods, savages, like those of Tierra del Fuego or Australia, who possess a semi-domestic dog, may not have existed in Egypt?

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我想，这个问题肯定是一笔糊涂账。但我可以在不涉及任何细节的情况下，在此声明，从地理等因素看，家狗从几个野生种遗传而来，我看可能性很大。至于绵羊和山羊，我还没有看法。从布莱斯（Blyth）先生告诉过我的关于印度瘤牛的习性、叫声、体质构造的事实看来，差不多可以确定它的原始祖先和欧洲牛是不同的；若干能干的鉴定家认为，欧洲牛有一个以上野生祖先。关于马，我同几个作者的意见相反，我有所保留地认为，所有的马族都来自一个野生祖先，理由无法在这里提出。布莱斯先生知识渊博，是我最敬重的，他认为所有鸡的品种都是野生印度鸡（Gallus bankiva，红原鸡）的后代。关于鸭和兔，有些品种彼此结构差异很大，我不怀疑，它们都是从普通野生鸭和野生兔传下来的。

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The whole subject must, I think, remain vague; nevertheless, I may, without here entering on any details, state that, from geographical and other considerations, I think it highly probable that our domestic dogs have descended from several wild species. In regard to sheep and goats I can form no opinion. I should think, from facts communicated to me by Mr. Blyth, on the habits, voice, and constitution, etc., of the humped Indian cattle, that these had descended from a different aboriginal stock from our European cattle; and several competent judges believe that these latter have had more than one wild parent. With respect to horses, from reasons which I cannot give here, I am doubtfully inclined to believe, in opposition to several authors, that all the races have descended from one wild stock. Mr. Blyth, whose opinion, from his large and varied stores of knowledge, I should value more than that of almost any one, thinks that all the breeds of poultry have proceeded from the common wild Indian fowl (Gallus bankiva). In regard to ducks and rabbits, the breeds of which differ considerably from each other in structure, I do not doubt that they all have descended from the common wild duck and rabbit.

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某些作者把若干家养族起源于多个原始祖先的学说引入极端，颇为荒谬。他们认为，每一个纯系繁殖的家养族，即使区别性状极其轻微，也各有其野生的原始型。照此说来，仅在欧洲一处，想必生存过不下于二十个野牛种，二十个野绵羊种，若干个野山羊种，甚至在英国一地也有若干个物种了。还有一位作者认为，先前英国所特有的绵羊野生种竟有十一个之多！如果记住，英国现在已没有一种特有的哺乳动物，法国和德国的不同，只有少数哺乳动物反之亦然，匈牙利、西班牙等也是这样，而这些国度各有若干特有的牛羊等品种，那么我们必须承认，许多家畜品种起源于欧洲；既然这些国家都没有拥有作为区别性亲种祖先的若干特有物种，那是从哪里来的呢？印度也是这样。即使是全世界的家狗品种，我完全承认可能是从几个野生种传下来的，也不能怀疑有大量的遗传性变异。意大利长驱跑狗、嗅血警犬、斗牛狗或布莱尼姆犬（Blenheim spaniel）等等同一切野生犬科动物如此不相像，有谁会相信与其酷似的动物在自然状态下自由生存过呢？常常有人信口说，所有的狗族都是由若干原始物种杂交而产生的，但是杂交只能获得好歹介于两亲之间的类型。如果用这一过程来说明几个家养族的起源，我们就必须承认一些极端类型，如意大利长驱跑狗、嗅血警犬、斗牛狗等，曾在野生状态下存在过。何况杂交产生不同族的可能性被大大夸张了。毫无疑问，辅助以对表现所需要的性状的个体杂种进行仔细选择，偶然的杂交可使一个族发生变异，但是要想从两个大相径庭的族或者物种，得到一个中间性的族，我难以置信。西布赖特（J. Sebright）爵士特意为了这一目的进行过实验，结果失败了。两个纯系品种第一次杂交后所产生的子代，其性状尚称一致，有时（我在鸽子中所发现）非常一致，一切似乎很简单；但是当这些杂种互相进行数代杂交之后，简直没有两个是彼此相像的。由此可见，该工作难上加难，甚至是毫无胜算了。当然，要从两个截然不同的品种得到折中品种，非得极端仔细，长期选择不可。我找不到任何记载，说明有由此搞成永久族的个案。

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The doctrine of the origin of our several domestic races from several aboriginal stocks, has been carried to an absurd extreme by some authors. They believe that every race which breeds true, let the distinctive characters be ever so slight, has had its wild prototype. At this rate there must have existed at least a score of species of wild cattle, as many sheep, and several goats in Europe alone, and several even within Great Britain. One author believes that there formerly existed in Great Britain eleven wild species of sheep peculiar to it! When we bear in mind that Britain has now hardly one peculiar mammal, and France but few distinct from those of Germany and conversely, and so with Hungary, Spain, etc., but that each of these kingdoms possesses several peculiar breeds of cattle, sheep, etc., we must admit that many domestic breeds have originated in Europe; for whence could they have been derived, as these several countries do not possess a number of peculiar species as distinct parent-stocks? So it is in India. Even in the case of the domestic dogs of the whole world, which I fully admit have probably descended from several wild species, I cannot doubt that there has been an immense amount of inherited variation. Who can believe that animals closely resembling the Italian greyhound, the bloodhound, the bull-dog, or Blenheim spaniel, etc.—so unlike all wild Canidae—ever existed freely in a state of nature? It has often been loosely said that all our races of dogs have been produced by the crossing of a few aboriginal species; but by crossing we can get only forms in some degree intermediate between their parents; and if we account for our several domestic races by this process, we must admit the former existence of the most extreme forms, as the Italian greyhound, bloodhound, bull-dog, etc., in the wild state. Moreover, the possibility of making distinct races by crossing has been greatly exaggerated. There can be no doubt that a race may be modified by occasional crosses, if aided by the careful selection of those individual mongrels, which present any desired character; but that a race could be obtained nearly intermediate between two extremely different races or species, I can hardly believe. Sir J. Sebright expressly experimentised for this object, and failed. The offspring from the first cross between two pure breeds is tolerably and sometimes (as I have found with pigeons) extremely uniform, and everything seems simple enough; but when these mongrels are crossed one with another for several generations, hardly two of them will be alike, and then the extreme difficulty, or rather utter hopelessness, of the task becomes apparent. Certainly, a breed intermediate between two very distinct breeds could not be got without extreme care and long-continued selection; nor can I find a single case on record of a permanent race having been thus formed.

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关于家鸽的品种。——我觉得用特殊类群进行研究总是最好的方法，考虑之后，便选取了家鸽。我养了每一个能买到、得到的品种，并且从世界若干地方得到了惠赠的各种鸽皮，特别是埃里奥特（W. Elliot）阁下从印度、默里（C. Murray）阁下从波斯寄来的。关于鸽类已经发表过许多论文，有多种不同文字，其中有些十分古老，因此很重要。我曾和几位养鸽名家交往，并且被接纳加入了伦敦的两个养鸽俱乐部。家鸽品种之多，令人惊异。比较瘤鼻鸽（English carrier）和短面翻飞鸽（short-faced tumbler），可以看出喙部的奇特差异，由此引起头骨的差异。瘤鼻鸽，特别是雄鸽，头部周围的皮也具有奇特发育的肉突；与此相伴随的还有很长的眼睑、很大的外鼻孔以及阔大的口。短面翻飞鸽的喙部外形差不多和雀科鸣禽（finch）相像；普通翻飞鸽有一种奇特的纯属遗传的习性，密集成群地在高空飞翔并且连续翻筋斗。侏儒鸽（runt）身体巨大，喙粗长，足亦大；有些大种家鸽的亚品种，颈项很长，有些翅和尾很长，有些尾特别短。巴巴里家鸽（barb）和瘤鼻鸽品种相近，但喙不长，而是短而阔。球胸鸽（pouter）的身体、翅、腿特别长，嗉囊异常发达，而且以膨胀为荣，很可以令人惊异，甚至发笑。浮羽鸽（turbit）的喙短，呈圆锥形，胸下有倒生的羽毛一列。它有一种习性，不断地微微膨胀食管上部。毛领鸽（Jacobin）的羽毛沿着颈背向前倒竖而成兜状；从身体的大小比例看来，其翅羽和尾羽颇长。顾名思义，帚鸽（trumpeter，意思是喇叭）和笑鸽（laughter）的叫声，与别的品种极不相同。扇尾鸽（fantail）有三十支甚至四十支尾羽，而不是庞大鸽科成员的正常数目——十二或十四支。它们的尾部羽毛都是展开的，并且竖立，优良的品种竟可头尾相触，尾脂腺颇为退化。此外还可举出若干差异比较小的品种。

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On the Breeds of the Domestic Pigeon.—Believing that it is always best to study some special group, I have, after deliberation, taken up domestic pigeons. I have kept every breed which I could purchase or obtain, and have been most kindly favoured with skins from several quarters of the world, more especially by the Honourable W. Elliot from India, and by the Honourable C. Murray from Persia. Many treatises in different languages have been published on pigeons, and some of them are very important, as being of considerable antiquity. I have associated with several eminent fanciers, and have been permitted to join two of the London Pigeon Clubs. The diversity of the breeds is something astonishing. Compare the English carrier and the short-faced tumbler, and see the wonderful difference in their beaks, entailing corresponding differences in their skulls. The carrier, more especially the male bird, is also remarkable from the wonderful development of the carunculated skin about the head, and this is accompanied by greatly elongated eyelids, very large external orifices to the nostrils, and a wide gape of mouth. The short-faced tumbler has a beak in outline almost like that of a finch; and the common tumbler has the singular and strictly inherited habit of flying at a great height in a compact flock, and tumbling in the air head over heels. The runt is a bird of great size, with long, massive beak and large feet; some of the sub-breeds of runts have very long necks, others very long wings and tails, others singularly short tails. The barb is allied to the carrier, but, instead of a very long beak, has a very short and very broad one. The pouter has a much elongated body, wings, and legs; and its enormously developed crop, which it glories in inflating, may well excite astonishment and even laughter. The turbit has a very short and conical beak, with a line of reversed feathers down the breast; and it has the habit of continually expanding slightly the upper part of the oesophagus. The Jacobin has the feathers so much reversed along the back of the neck that they form a hood, and it has, proportionally to its size, much elongated wing and tail feathers. The trumpeter and laugher, as their names express, utter a very different coo from the other breeds. The fantail has thirty or even forty tail-feathers, instead of twelve or fourteen, the normal number in all members of the great pigeon family; and these feathers are kept expanded, and are carried so erect that in good birds the head and tail touch; the oil-gland is quite aborted. Several other less distinct breeds might have been specified.

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这几个品种的骨骼，其面骨的长度、宽度、曲度的发育大有差异。下颚的枝骨形状以及长宽，都有极显著的变异。尾椎和荐椎的数目有变异；肋骨的数目也有变异，它们的相对宽度和突起的有无，也有变异。胸骨孔的大小形状有显著变异；叉骨两枝的开度和相对长度也是如此。口裂的相对阔度，眼睑、鼻孔、舌（不总是和喙的长度严格相关）的相对长度，嗉囊和上部食管的大小；尾脂腺的发育和退化；第一列翅羽和尾羽的数目；翅和尾的彼此相对长度及其和身体的相对长度；腿和脚的相对长度；趾上鳞板的数目，趾间皮膜的发达程度，这一切构造都是易于变异的。羽毛完全出齐的时期有变异，孵化后雏鸽的绒毛覆盖状态也是如此。卵的形状和大小有变异。飞行姿势有显著差异，某些品种的叫声和性情有显著差异。最后，还有某些品种，雌雄间彼此略有差异。

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In the skeletons of the several breeds, the development of the bones of the face in length and breadth and curvature differs enormously. The shape, as well as the breadth and length of the ramus of the lower jaw, varies in a highly remarkable manner. The number of the caudal and sacral vertebrae vary; as does the number of the ribs, together with their relative breadth and the presence of processes. The size and shape of the apertures in the sternum are highly variable; so is the degree of divergence and relative size of the two arms of the furcula. The proportional width of the gape of mouth, the proportional length of the eyelids, of the orifice of the nostrils, of the tongue (not always in strict correlation with the length of beak), the size of the crop and of the upper part of the oesophagus; the development and abortion of the oil-gland; the number of the primary wing and caudal feathers; the relative length of wing and tail to each other and to the body; the relative length of leg and of the feet; the number of scutellae on the toes, the development of skin between the toes, are all points of structure which are variable. The period at which the perfect plumage is acquired varies, as does the state of the down with which the nestling birds are clothed when hatched. The shape and size of the eggs vary. The manner of flight differs remarkably; as does in some breeds the voice and disposition. Lastly, in certain breeds, the males and females have come to differ to a slight degree from each other.

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总共至少可以选出二十种鸽，如果拿给鸟学家去看，并且告诉他，这些都是野鸟，我想他一定会把它们列为明确定义的物种的。另外，我不相信任何鸟学家会把瘤鼻鸽、短面翻飞鸽、大种家鸽、巴巴里家鸽、球胸鸽以及扇尾鸽列为同属；特别是把这些品种每一个中的若干个纯粹遗传的亚品种（他会叫作物种）指给他看时。

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Altogether at least a score of pigeons might be chosen, which if shown to an ornithologist, and he were told that they were wild birds, would certainly, I think, be ranked by him as well-defined species. Moreover, I do not believe that any ornithologist would place the English carrier, the short-faced tumbler, the runt, the barb, pouter, and fantail in the same genus; more especially as in each of these breeds several truly-inherited sub-breeds, or species as he might have called them, could be shown him.

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鸽类品种间的差异固然很大，但我充分相信学者们的一般意见是正确的，即它们都是从野生岩鸽（Columba livia）传下来的，这个名称之下还包含几个彼此差异极细微的地方族，即亚种。鉴于我持这一信念的理由中有若干在某种程度上也适用于其他个案，就在这里概括说一说吧。如果这几个品种不是变种，不是来源于岩鸽，那至少必须是从七八种原始祖先传下来的；因为以更少的数目进行杂交，就不可能造成现今这样的家养品种。例如两个品种进行杂交，如果亲代之一不具有大嗉囊的性状，怎能产生球胸鸽呢？这些假定的原始祖先，必定都是岩鸽，它们不在树上生育，也不喜欢在树上栖息。但是，除了野生岩鸽及其地理亚种外，所知道的其他岩鸽只有两三种，而它们都不具有家养品种的任何性状。因此，所假定的那些原始祖先要么在鸽子最初驯化的那些地方至今还生存着，只是鸟类学家不知道罢了，但考虑到它们的大小、习性和显著的性状而言，似乎不会不为人知的；要么它们在野生状态下想必都灭绝了。但是，在岩崖上生育的善飞的鸟，不大可能被消灭；而具有家养品种同样习性的普通岩鸽，即使在英国的小岛、地中海的海岸上，也都没有消灭。因此，假定与岩鸽习性相似的这么多的物种已绝灭，我看是十分轻率的推测。另外，上述若干家养品种曾被运送到世界各地，想必有几种被带回原产地；但是，除了鸠鸽（dovecot-pigeon）这种稍微改变的岩鸽在若干地方变为野生以外，没有一个品种变为野生的。再者，最近的经验表明，使野生动物在家养状况下自由繁育极其困难；然而，根据家鸽多源说，必须假定至少有七八个物种在古代已由半开化人彻底驯化，所以能在笼养下大量繁殖。

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Great as the differences are between the breeds of pigeons, I am fully convinced that the common opinion of naturalists is correct, namely, that all have descended from the rock-pigeon (Columba livia), including under this term several geographical races or sub-species, which differ from each other in the most trifling respects. As several of the reasons which have led me to this belief are in some degree applicable in other cases, I will here briefly give them. If the several breeds are not varieties, and have not proceeded from the rock-pigeon, they must have descended from at least seven or eight aboriginal stocks; for it is impossible to make the present domestic breeds by the crossing of any lesser number: how, for instance, could a pouter be produced by crossing two breeds unless one of the parent-stocks possessed the characteristic enormous crop? The supposed aboriginal stocks must all have been rock-pigeons, that is, not breeding or willingly perching on trees. But besides C. livia, with its geographical sub-species, only two or three other species of rock-pigeons are known; and these have not any of the characters of the domestic breeds. Hence the supposed aboriginal stocks must either still exist in the countries where they were originally domesticated, and yet be unknown to ornithologists; and this, considering their size, habits, and remarkable characters, seems very improbable; or they must have become extinct in the wild state. But birds breeding on precipices, and good fliers, are unlikely to be exterminated; and the common rock-pigeon, which has the same habits with the domestic breeds, has not been exterminated even on several of the smaller British islets, or on the shores of the Mediterranean. Hence the supposed extermination of so many species having similar habits with the rock-pigeon seems to me a very rash assumption. Moreover, the several above-named domesticated breeds have been transported to all parts of the world, and, therefore, some of them must have been carried back again into their native country; but not one has ever become wild or feral, though the dovecot-pigeon, which is the rock-pigeon in a very slightly altered state, has become feral in several places. Again, all recent experience shows that it is most difficult to get any wild animal to breed freely under domestication; yet on the hypothesis of the multiple origin of our pigeons, it must be assumed that at least seven or eight species were so thoroughly domesticated in ancient times by half-civilized man, as to be quite prolific under confinement.

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有一个依我看似乎分量很重，并且适用于若干其他个案的论点是，上述诸品种虽然体质、习性、叫声、颜色以及大部分构造与野生岩鸽大体相同，但一部分构造是极异常的。在整个鸽大科里，找不到一种像瘤鼻鸽、短面翻飞鸽、巴巴里家鸽的喙；像毛领鸽的倒羽毛；像球胸鸽的嗉囊；像扇尾鸽的尾羽。因此必须假定，不但半开化人成功地彻底驯化了几个物种，而且有意无意地选出了特别异常的物种；此外，这些物种以后都完全灭绝了，或者湮没无闻了。看来，这许多奇怪的偶然性是绝对不会发生的。

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An argument, as it seems to me, of great weight, and applicable in several other cases, is, that the above-specified breeds, though agreeing generally in constitution, habits, voice, colouring, and in most parts of their structure, with the wild rock-pigeon, yet are certainly highly abnormal in other parts of their structure: we may look in vain throughout the whole great family of Columbidae for a beak like that of the English carrier, or that of the short-faced tumbler, or barb; for reversed feathers like those of the jacobin; for a crop like that of the pouter; for tail-feathers like those of the fantail. Hence it must be assumed not only that half-civilized man succeeded in thoroughly domesticating several species, but that he intentionally or by chance picked out extraordinarily abnormal species; and further, that these very species have since all become extinct or unknown. So many strange contingencies seem to me improbable in the highest degree.

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有关鸽类颜色的一些事实很值得考察。岩鸽是深灰青色的，尾部呈白色（印度的亚种——斯特里克兰的青色岩鸽［C. intermedia］尾部呈青色），尾端有一暗色横带，外侧尾羽的外缘基部呈白色，翅膀上有两条黑带。一些半家养的品种和一些看起来真正的野生品种，翅上除有两条黑带之外，更杂有黑色方条纹。全科的任何其他物种都不同时出现这几种标记。而在每一个家养品种里，以良种鸽为例，所有上述标记，甚至外尾羽的白边，有时都是充分发育同时出现。而且，当两个完全不同品种的鸽子进行杂交，虽然都不呈青色，没有上述标记，但其杂种后代却很容易突然获得这些性状。我用几只纯白色扇尾鸽同几只纯黑色巴巴里家鸽进行杂交，它们的杂种是斑驳的褐色和黑色。随后我用这些杂种再进行杂交，纯白色扇尾鸽同纯黑色巴巴里家鸽产生的一只孙辈鸽子，竟然具有任何野生岩鸽一样美丽的青色、白尾、两条黑翼带以及具有条纹和白边的尾羽！如果一切家养品种都是从岩鸽传下来的，根据众所周知的返祖遗传原理，我们就能够理解这些事实。但是，如果否认这一点，就必须做出下列两个很不可能的假设之一。第一，所有想象的各原始祖先，都具有岩鸽那样的颜色和标记，可是没有其他现存物种具有这样的颜色和标记，所以各个品种可能都有重现同样颜色和标记的倾向；第二，各品种，即使是最纯粹的，也曾在十二代，最多二十代之内同岩鸽交配过，我说在十二代或二十代之内，是因为不曾见到有任何事实表明，杂种后代能够返祖到二十代以上。只杂交过一次的品种重现从这次杂交中得到的任何性状的倾向，自然而然越来越弱，因为在以后各代里外来血统将逐渐减少。但是，如果不曾杂交过，而两个亲种都有重现前几代已经消失了的性状的倾向，那么这一倾向能不减弱地遗传到无数代，尽管我们知道有相反的情况。关于遗传问题的论文常常把这两种不同的个案混淆在一起。

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Some facts in regard to the colouring of pigeons well deserve consideration. The rock-pigeon is of a slaty-blue, and has a white rump (the Indian sub-species, C. intermedia of Strickland, having it bluish); the tail has a terminal dark bar, with the bases of the outer feathers externally edged with white; the wings have two black bars; some semi-domestic breeds and some apparently truly wild breeds have, besides the two black bars, the wings chequered with black. These several marks do not occur together in any other species of the whole family. Now, in every one of the domestic breeds, taking thoroughly well-bred birds, all the above marks, even to the white edging of the outer tail-feathers, sometimes concur perfectly developed. Moreover, when two birds belonging to two distinct breeds are crossed, neither of which is blue or has any of the above-specified marks, the mongrel offspring are very apt suddenly to acquire these characters; for instance, I crossed some uniformly white fantails with some uniformly black barbs, and they produced mottled brown and black birds; these I again crossed together, and one grandchild of the pure white fantail and pure black barb was of as beautiful a blue colour, with the white rump, double black wing-bar, and barred and white-edged tail-feathers, as any wild rock-pigeon! We can understand these facts, on the well-known principle of reversion to ancestral characters, if all the domestic breeds have descended from the rock-pigeon. But if we deny this, we must make one of the two following highly improbable suppositions. Either, firstly, that all the several imagined aboriginal stocks were coloured and marked like the rock-pigeon, although no other existing species is thus coloured and marked, so that in each separate breed there might be a tendency to revert to the very same colours and markings. Or, secondly, that each breed, even the purest, has within a dozen or, at most, within a score of generations, been crossed by the rock-pigeon: I say within a dozen or twenty generations, for we know of no fact countenancing the belief that the child ever reverts to some one ancestor, removed by a greater number of generations. In a breed which has been crossed only once with some distinct breed, the tendency to reversion to any character derived from such cross will naturally become less and less, as in each succeeding generation there will be less of the foreign blood; but when there has been no cross with a distinct breed, and there is a tendency in both parents to revert to a character, which has been lost during some former generation, this tendency, for all that we can see to the contrary, may be transmitted undiminished for an indefinite number of generations. These two distinct cases are often confounded in treatises on inheritance.

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最后，所有鸽的家养品种间杂种都是完全能育的。这一点我有自己的观察结果，故意找了最不同的品种。然而两个明显不同动物种的杂种，本身完全能育的，则很难找到个案，也许是根本不存在。有些作者认为，长期连续的家养可消除这种种间不育性的强烈倾向：根据狗类的历史来看，我看这种假设如果用于彼此密切亲缘的物种，有一定的可能性，尽管没有一例实验加以支持。但是，如果把该假设牵强附会，说始祖就具有像今日的瘤鼻鸽、翻飞鸽、球胸鸽和扇尾鸽那样显著差异的物种，会产生完全能育的后代，我看未免过于唐突。

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Lastly, the hybrids or mongrels from between all the domestic breeds of pigeons are perfectly fertile. I can state this from my own observations, purposely made on the most distinct breeds. Now, it is difficult, perhaps impossible, to bring forward one case of the hybrid offspring of two animals clearly distinct being themselves perfectly fertile. Some authors believe that long-continued domestication eliminates this strong tendency to sterility: from the history of the dog I think there is some probability in this hypothesis, if applied to species closely related together, though it is unsupported by a single experiment. But to extend the hypothesis so far as to suppose that species, aboriginally as distinct as carriers, tumblers, pouters, and fantails now are, should yield offspring perfectly fertile, inter se, seems to me rash in the extreme.

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鉴于人类不可能曾使七八个所谓的鸽种在家养状况下自由繁殖；这些所谓的物种从未在野生状态下被发现过，而且也没有在何处变为野生的；这些物种在大多数方面很像岩鸽，但同鸽科的其他物种相比较，却有某些极异常的性状；无论是纯种繁育、杂交，所有品种都会偶尔出现青色和各种标记；杂种后代完全能生育，综上所述，毋庸置疑，所有家养品种都是从野生岩鸽及其地理亚种传下来的。

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From these several reasons, namely, the improbability of man having formerly got seven or eight supposed species of pigeons to breed freely under domestication; these supposed species being quite unknown in a wild state, and their becoming nowhere feral; these species having very abnormal characters in certain respects, as compared with all other Columbidae, though so like in most other respects to the rock-pigeon; the blue colour and various marks occasionally appearing in all the breeds, both when kept pure and when crossed; the mongrel offspring being perfectly fertile;—from these several reasons, taken together, I can feel no doubt that all our domestic breeds have descended from the Columba livia with its geographical sub-species.

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为了支持此观点，我补充如下：第一，欧洲和印度已发现野生岩鸽能驯养，并且在习性和大多数构造特点上和所有家鸽品种相一致。第二，虽然瘤鼻鸽、短面翻飞鸽在某些性状上和岩鸽大不相同，但是，把这两个族的若干亚品种加以比较，特别是从远地带来的，可以在极端的构造之间组成几乎完整的系列。第三，每一品种的主要区别性状都是尤其易变异的，如瘤鼻鸽的垂肉、长喙，翻飞鸽的短喙，扇尾鸽的尾羽数目，这一点的解释，等论到“选择”的时候便清清楚楚了。第四，鸽类受到许多人极细心的观察、照料和喜爱，它们在世界的若干地方被饲育了数千年。根据莱普修斯（Lepsius）教授向我指出的，关于鸽类的最早记载约在公元前3000年，在埃及第五王朝；但伯奇（Birch）先生告诉我说，在此前的一个王朝已有鸽名记载在菜单上了。普林尼（Pliny）说，罗马时代鸽的价格极高；“嗨，他们居然要核算它们的谱系和族”。印度阿克巴汗（Akbar Khan）非常重视鸽子，大约在1600年，养在宫中的鸽子就不下两万只。宫廷史官写道：“伊朗王和图兰王曾送给他一些珍稀的鸽子；陛下通过杂交，惊人地改良了它们，前人从未用过这方法。”差不多在同一时代，荷兰人也像古罗马人那样对鸽子趋之若鹜。这种关注对解释鸽类所发生的大量变异是极其重要的，详见“选择”章节。后文还可知道，为什么鸽种常常具有畸形的性状。雄鸽和雌鸽容易终身相配，这也是产生不同品种的有利条件；这样，就能把不同品种饲养在一个鸟棚里了。

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In favour of this view, I may add, firstly, that C. livia, or the rock-pigeon, has been found capable of domestication in Europe and in India; and that it agrees in habits and in a great number of points of structure with all the domestic breeds. Secondly, although an English carrier or short-faced tumbler differs immensely in certain characters from the rock-pigeon, yet by comparing the several sub-breeds of these breeds, more especially those brought from distant countries, we can make an almost perfect series between the extremes of structure. Thirdly, those characters which are mainly distinctive of each breed, for instance the wattle and length of beak of the carrier, the shortness of that of the tumbler, and the number of tail-feathers in the fantail, are in each breed eminently variable; and the explanation of this fact will be obvious when we come to treat of selection. Fourthly, pigeons have been watched, and tended with the utmost care, and loved by many people. They have been domesticated for thousands of years in several quarters of the world; the earliest known record of pigeons is in the fifth Aegyptian dynasty, about 3000 B.C., as was pointed out to me by Professor Lepsius; but Mr. Birch informs me that pigeons are given in a bill of fare in the previous dynasty. In the time of the Romans, as we hear from Pliny, immense prices were given for pigeons; “nay, they are come to this pass, that they can reckon up their pedigree and race.” Pigeons were much valued by Akber Khan in India, about the year 1600; never less than 20000 pigeons were taken with the court. “The monarchs of Iran and Turan sent him some very rare birds;” and, continues the courtly historian, “His Majesty by crossing the breeds, which method was never practised before, has improved them astonishingly.” About this same period the Dutch were as eager about pigeons as were the old Romans. The paramount importance of these considerations in explaining the immense amount of variation which pigeons have undergone, will be obvious when we treat of Selection. We shall then, also, see how it is that the breeds so often have a somewhat monstrous character. It is also a most favourable circumstance for the production of distinct breeds, that male and female pigeons can be easily mated for life; and thus different breeds can be kept together in the same aviary.

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我已对家鸽的可能起源做了若干论述，但仍然觉得不够。我最初养鸽并观察几类鸽子的时候，很清楚它们都是纯种，我也充分体会到，同样很难相信它们都起源于一个共同祖先，正如任何学者难于对自然界许多雀科鸣禽的物种或其他大类群的鸟做出同样的结论。有一种情形我印象很深，就是所有的家养动物的饲养者和植物的栽培者——我曾经和他们交谈过或者读过他们的文章——都坚信他们所养育的若干品种是从各种不同的原始物种传下来的。请你也像我那样，向赫里福德（Hereford）牛的知名饲养者问一问，他的牛是否从长角牛（long-horns）传下来的，他就会嘲笑你。我遇见过的鸽、鸡、鸭或兔的饲养者，无不坚信各个主要品种是从某一个物种传下来的。凡·蒙斯（Van Mons）关于梨和苹果的论文，全然不信几类苹果，如“里伯斯顿小苹果”“考得林青苹果”，能够从同一株树的种子生出来。其他例子不胜枚举。我想，解释是简单不过的：根据长期不断的研究，他们对几个族间的差异印象深刻；他们熟知各族微有变异，他们因为选择这种轻微差异而得了奖，却无视所有的一般论点，而且也不肯在心里把许多连续世代累积起来的轻微差异总结一下。那些学者所知道的遗传法则，远不如饲养者，对于悠长的世代相传系统中的中间环节也不如饲养者熟悉，饲养者都承认许多家养族是从同一祖先传下来的——当他们嘲笑自然状态下的物种是其他物种的直系后代这个观念时，难道不会学一学谨慎这一课吗？

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I have discussed the probable origin of domestic pigeons at some, yet quite insufficient, length; because when I first kept pigeons and watched the several kinds, knowing well how true they bred, I felt fully as much difficulty in believing that they could ever have descended from a common parent, as any naturalist could in coming to a similar conclusion in regard to the many species of finches, or other large groups of birds, in nature. One circumstance has struck me much; namely, that all the breeders of the various domestic animals and the cultivators of plants, with whom I have ever conversed, or whose treatises I have read, are firmly convinced that the several breeds to which each has attended, are descended from so many aboriginally distinct species. Ask, as I have asked, a celebrated raiser of Hereford cattle, whether his cattle might not have descended from long-horns, and he will laugh you to scorn. I have never met a pigeon, or poultry, or duck, or rabbit fancier, who was not fully convinced that each main breed was descended from a distinct species. Van Mons, in his treatise on pears and apples, shows how utterly he disbelieves that the several sorts, for instance a Ribston-pippin or Codlin-apple, could ever have proceeded from the seeds of the same tree. Innumerable other examples could be given. The explanation, I think, is simple: from long-continued study they are strongly impressed with the differences between the several races; and though they well know that each race varies slightly, for they win their prizes by selecting such slight differences, yet they ignore all general arguments, and refuse to sum up in their minds slight differences accumulated during many successive generations. May not those naturalists who, knowing far less of the laws of inheritance than does the breeder, and knowing no more than he does of the intermediate links in the long lines of descent, yet admit that many of our domestic races have descended from the same parents—may they not learn a lesson of caution, when they deride the idea of species in a state of nature being lineal descendants of other species?

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选择。——现在简要地考虑一下，家养族从一个物种或从几个近似物种产生出来的步骤。有些微小效果也许可以归因于外界生活条件的直接作用，有些微小效果可以归因于习性；但是若要用这等力量来说明驭马和赛马、长驱跑狗和嗅血警犬、瘤鼻鸽和翻飞鸽之间的差异，那就未免胆大妄为了。家养族最显著的特色之一，是我们看中了它们的适应性，倒不是为了动植物自身的利益，而是为了人的使用或爱好。有些于人类有用的变异大概是突然发生的，一步到位的。例如，许多学者认为，生有刺钩的起绒草（fuller’s teazle）——这些刺钩是任何机械装置所不及的——只是野生川续断草（Dipsacus）的变种而已，而这种变化量会在一株实生苗上突然冒出。转叉狗（turnspit dog）大概也是这样起源的；我们知道安康羊（ancon sheep）的情形也是如此。但是，当我们比较驭马和赛马，单峰骆驼和双峰骆驼，适于耕地和适于山地牧场，以及羊毛用途各异的不同种类的绵羊时，当我们比较以各种用途为人类服务的许多狗品种时，当我们将争强好胜的斗鸡和很少争斗的品种比较，和从来不孵卵的蛋用鸡、小巧玲珑的矮脚鸡（bantam）比较时，当我们比较无数的农艺植物、蔬菜植物、果树植物以及花卉植物的族时，它们在不同的季节以不同的目的有益于人类，或者美丽非凡令人赏心悦目；我想，我们必须超越区区的变异性之外了。我们无法设想所有品种都是突然产生的，而一产生就像今日所看到的那样完善有用。其实，在若干个案上，我们知道它们的历史并不是这样的。关键就在于人类累积选择的力量：自然给予了连续的变异，人类在对自己有用的一定方向上积累了这些变异。在这种意义上，才可以说人类为自己制造了有用的品种。

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Selection.—Let us now briefly consider the steps by which domestic races have been produced, either from one or from several allied species. Some little effect may, perhaps, be attributed to the direct action of the external conditions of life, and some little to habit; but he would be a bold man who would account by such agencies for the differences of a dray and race horse, a greyhound and bloodhound, a carrier and tumbler pigeon. One of the most remarkable features in our domesticated races is that we see in them adaptation, not indeed to the animal’s or plant’s own good, but to man’s use or fancy. Some variations useful to him have probably arisen suddenly, or by one step; many botanists, for instance, believe that the fuller’s teazle, with its hooks, which cannot be rivalled by any mechanical contrivance, is only a variety of the wild Dipsacus; and this amount of change may have suddenly arisen in a seedling. So it has probably been with the turnspit dog; and this is known to have been the case with the ancon sheep. But when we compare the dray-horse and race-horse, the dromedary and camel, the various breeds of sheep fitted either for cultivated land or mountain pasture, with the wool of one breed good for one purpose, and that of another breed for another purpose; when we compare the many breeds of dogs, each good for man in very different ways; when we compare the game-cock, so pertinacious in battle, with other breeds so little quarrelsome, with “everlasting layers” which never desire to sit, and with the bantam so small and elegant; when we compare the host of agricultural, culinary, orchard, and flower-garden races of plants, most useful to man at different seasons and for different purposes, or so beautiful in his eyes, we must, I think, look further than to mere variability. We cannot suppose that all the breeds were suddenly produced as perfect and as useful as we now see them; indeed, in several cases, we know that this has not been their history. The key is man’s power of accumulative selection: nature gives successive variations; man adds them up in certain directions useful to him. In this sense he may be said to make for himself useful breeds.

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这种选择原则的伟大力量不是凭空想象的。确实有几位优秀的饲养者，甚至在一生的时间里，就大大地改变了某些牛羊品种。要充分认识到他们的作为，有必要阅读有关这个问题的论文，有必要考察那些动物。饲养者习惯说动物的体制是可塑的，可以几乎随心所欲地加以塑造。如果篇幅容许，可以从权威的著作中大量引述这种记载。尤亚特（Youatt）对农艺著作的通晓，几乎无人能比，自己就是一位极优秀的动物鉴定者，称选择原则“可以使农学家不仅改变畜群性状，而且加以彻底改造。选择是魔杖，可以随心所欲地让任何形体和模式出生”。萨默维尔（Somerville）勋爵谈到养羊的成就时曾说：“好像饲养者用粉笔在墙壁上画出了完美无缺的形体，然后赋予它生命。”神乎其技的饲养者西布赖特谈到鸽子时说过“他三年就可以产生任何给定的羽毛，而获得脑袋和喙则需要六年”。在撒克逊，选择原则对于美利奴羊（merino sheep）的重要性已得到充分认识，人们以此为业：把绵羊摆在桌子上研究，就像鉴赏家鉴定绘画那样；一共研究三次，各间隔几个月，每次都在羊身上做记号进行分类，最后选择最优良的，作为繁育之用。

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The great power of this principle of selection is not hypothetical. It is certain that several of our eminent breeders have, even within a single lifetime, modified to a large extent some breeds of cattle and sheep. In order fully to realise what they have done, it is almost necessary to read several of the many treatises devoted to this subject, and to inspect the animals. Breeders habitually speak of an animal’s organisation as something quite plastic, which they can model almost as they please. If I had space I could quote numerous passages to this effect from highly competent authorities. Youatt, who was probably better acquainted with the works of agriculturists than almost any other individual, and who was himself a very good judge of an animal, speaks of the principle of selection as “that which enables the agriculturist, not only to modify the character of his flock, but to change it altogether. It is the magician’s wand, by means of which he may summon into life whatever form and mould he pleases.” Lord Somerville, speaking of what breeders have done for sheep, says:—“It would seem as if they had chalked out upon a wall a form perfect in itself, and then had given it existence.” That most skilful breeder, Sir John Sebright, used to say, with respect to pigeons, that “he would produce any given feather in three years, but it would take him six years to obtain head and beak.” In Saxony the importance of the principle of selection in regard to merino sheep is so fully recognised, that men follow it as a trade: the sheep are placed on a table and are studied, like a picture by a connoisseur; this is done three times at intervals of months, and the sheep are each time marked and classed, so that the very best may ultimately be selected for breeding.

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英国饲养者的实际成就，可以用优良谱系动物的高昂价格来证明，更何况现在已经出口世界各地。这种改良，决不是普遍归功于不同品种的杂交；最优秀的饲养者都强烈反对这种做法，除了有时杂交亲缘密切的亚品种之外。而在杂交进行以后，严之又严的选择甚至比普通个案更不可或缺。如果选择仅仅在于分离出某个很独特的变种加以繁殖，选择原则就显而易见，不值一提；但选择的重要性却在于鉴别未经训练的眼睛所绝对觉察不出的差异——例如我就实在察觉不出这些差异——并且使之在若干连续世代里，向一个方向累积起来而产生极大的效果。若论准确的眼力和判断力，能成为饲养家的，何止千里挑一。如果有此等天赋，潜心研究它多年，并且坚持不懈，奋斗终生，就会功成名就，可望做出巨大改良；不具备这种天赋的，必败无疑。很少人心悦诚服地相信，连成为熟练的养鸽者，也必须有天赋的才能和多年的实践。

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What English breeders have actually effected is proved by the enormous prices given for animals with a good pedigree; and these have now been exported to almost every quarter of the world. The improvement is by no means generally due to crossing different breeds; all the best breeders are strongly opposed to this practice, except sometimes amongst closely allied sub-breeds. And when a cross has been made, the closest selection is far more indispensable even than in ordinary cases. If selection consisted merely in separating some very distinct variety, and breeding from it, the principle would be so obvious as hardly to be worth notice; but its importance consists in the great effect produced by the accumulation in one direction, during successive generations, of differences absolutely inappreciable by an uneducated eye—differences which I for one have vainly attempted to appreciate. Not one man in a thousand has accuracy of eye and judgment sufficient to become an eminent breeder. If gifted with these qualities, and he studies his subject for years, and devotes his lifetime to it with indomitable perseverance, he will succeed, and may make great improvements; if he wants any of these qualities, he will assuredly fail. Few would readily believe in the natural capacity and years of practice requisite to become even a skilful pigeon-fancier.

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园艺家也遵循相同的原则；但植物的变异常常更易突发。没有人会设想，最精选的生物是原始祖先一次变异产生的。我们有若干个案可资证明，存有精确的档案；如普通醋栗（common gooseberry）的果实是逐渐增大的，就是一个很小的例证。把今日的花同仅仅二三十年前所画的花相比较，就可看到花卉栽培家对许多花做出了令人惊讶的改良。一旦植物的族很好地固定下来，种子繁育者并不是采选最好的植株，而仅仅是巡视苗床，拔除那些劣种，人们把那些脱离标准型的劣种植株叫作“无赖汉”。实际上，对于动物也同样采用这种选择方法；没有人会粗枝大叶地用最劣的动物去繁殖。

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The same principles are followed by horticulturists; but the variations are here often more abrupt. No one supposes that our choicest productions have been produced by a single variation from the aboriginal stock. We have proofs that this is not so in some cases, in which exact records have been kept; thus, to give a very trifling instance, the steadily-increasing size of the common gooseberry may be quoted. We see an astonishing improvement in many florists’ flowers, when the flowers of the present day are compared with drawings made only twenty or thirty years ago. When a race of plants is once pretty well established, the seed-raisers do not pick out the best plants, but merely go over their seed-beds, and pull up the “rogues,” as they call the plants that deviate from the proper standard. With animals this kind of selection is, in fact, also followed; for hardly any one is so careless as to allow his worst animals to breed.

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关于植物，还有一种方法可以观察选择的累积效果，在花园里比较同种里不同变种的花所表现的多样性；在菜园里把植物的叶、荚、块茎或任何其他有价值部分，在与同一变种的花相比较时所表现的多样性；在果园里把同种的果实在与同一批变种的叶和花相比较时所表现的多样性。看看圆白菜的叶是何等相异，而花又是何等极其相似；三色堇的花是何等相异，而叶又是何等相似；各类醋栗果实的大小、颜色、形状、茸毛是何等相异，而它们的花所表现的差异却极微。倒不是说在某一点上差异很大的变种，在所有其他各点上就毫无差异；这种情况是绝无仅有的。相关生长法则的重要性决不应该忽视，它能保证某些差异的发生；但是，一般地说，我不能怀疑，无论对叶、花，还是对果实的微小变异进行连续选择，就会产生主要在这些性状上有所差异的族。

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In regard to plants, there is another means of observing the accumulated effects of selection—namely, by comparing the diversity of flowers in the different varieties of the same species in the flower-garden; the diversity of leaves, pods, or tubers, or whatever part is valued, in the kitchen-garden, in comparison with the flowers of the same varieties; and the diversity of fruit of the same species in the orchard, in comparison with the leaves and flowers of the same set of varieties. See how different the leaves of the cabbage are, and how extremely alike the flowers; how unlike the flowers of the heartsease are, and how alike the leaves; how much the fruit of the different kinds of gooseberries differ in size, colour, shape, and hairiness, and yet the flowers present very slight differences. It is not that the varieties which differ largely in some one point do not differ at all in other points; this is hardly ever, perhaps never, the case. The laws of correlation of growth, the importance of which should never be overlooked, will ensure some differences; but, as a general rule, I cannot doubt that the continued selection of slight variations, either in the leaves, the flowers, or the fruit, will produce races differing from each other chiefly in these characters.

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也许有人会唱反调说，选择原则沦落为循规蹈矩的做法，充其量才七十五年的光景。的确，近年来人们是对它更加关注了，就这问题发表了许多论文，我还要加一句，相应的，其成果也出得快，而且影响大。但是，说该原则是近代的发现，就大错特错了。我可以引用古代著作中若干实例，说明那时已经充分认识到这一原则的重要性。英国历史上的蒙昧未开化时代，常进口精选的动物，并且制订了防止出口的法律；明令规定，马的体量不到一定尺寸就要加以消灭，这相当于苗圃工人拔除植物的“无赖汉”。我看到中国古代的百科全书清楚记载着选择原则。有些罗马经典著作罗列了明确的选择规则。《圣经·创世记》里就阐明，早在那个时期已经注意家畜的颜色了。现在，未开化人有时使家狗和野生犬科动物杂交，以改良品种，古代也曾这样做过，有普林尼的文章为证。南非的未开化人依据挽牛的颜色配对，有些爱斯基摩人对于雪橇狗也这样做。利文斯通（Livingstone）说，未曾与欧洲人接触过的非洲内陆的黑人极重视优良的家畜。某些这种事实虽然并未说明实际的选择过程，但明确了古代人密切关注家畜的繁育，而现今最不开化的人也一样。既然优劣品质的遗传如此明显，若对动植物的繁育不重视，那的确是稀奇古怪了。

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It may be objected that the principle of selection has been reduced to methodical practice for scarcely more than three-quarters of a century; it has certainly been more attended to of late years, and many treatises have been published on the subject; and the result, I may add, has been, in a corresponding degree, rapid and important. But it is very far from true that the principle is a modern discovery. I could give several references to the full acknowledgment of the importance of the principle in works of high antiquity. In rude and barbarous periods of English history choice animals were often imported, and laws were passed to prevent their exportation: the destruction of horses under a certain size was ordered, and this may be compared to the “roguing” of plants by nurserymen. The principle of selection I find distinctly given in an ancient Chinese encyclopaedia. Explicit rules are laid down by some of the Roman classical writers. From passages in Genesis, it is clear that the colour of domestic animals was at that early period attended to. Savages now sometimes cross their dogs with wild canine animals, to improve the breed, and they formerly did so, as is attested by passages in Pliny. The savages in South Africa match their draught cattle by colour, as do some of the Esquimaux their teams of dogs. Livingstone shows how much good domestic breeds are valued by the negroes of the interior of Africa who have not associated with Europeans. Some of these facts do not show actual selection, but they show that the breeding of domestic animals was carefully attended to in ancient times, and is now attended to by the lowest savages. It would, indeed, have been a strange fact, had attention not been paid to breeding, for the inheritance of good and bad qualities is so obvious.

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目前，饲养家们都按照明确的目的，试用循规蹈矩的选择，来形成优于国内现存种类的新品系或亚品种。但是，为了论述目的，我们更重视某一选择方式，或可称为无意识的选择，因为人人都想拥有最优良的动物个体并加以繁育。例如，打算养指示犬（pointers）的人自然会竭力搜求良种狗，然后用自己拥有的最优良的狗进行繁育，但他并没有持久改变这一品种的期望。然而，我并不怀疑，如果把这一程序继续若干世纪，将会改良并且改变任何品种，正如贝克韦尔（Bakewell）、科林斯（Collins）等等根据同样的程序，只是进行得更循规蹈矩，曾经在他们一生中大大地改变了牛的体形和品质。除非在很久以前，对有关品种就进行实际的计量或细心的描绘以供比较，这种缓慢而不易察觉的变化就永远无法辨识。然而，在某些个案下，同一品种没有变化或略有变化的个体生存在文明落后的地区也是有的，在那里品种是很少改良的。有理由相信，查理王的长耳猎狗自从该朝代以来已经无意识地大大改变了。某些高级权威相信，塞特谍犬（setter）直接来自长耳猎狗，大概是缓慢改变而来的。我们知道，英国指示犬在上一世纪内发生了大变，并且人们相信这次变化的发生，主要是和猎狐狗（fox-hound）杂交所致；但是我们所关心的是：这种变化是无意识地、缓慢地进行的，然而效果却非常显著，虽然以前的西班牙指示犬确实是从西班牙传来的，但博罗（Barrow）先生告诉我说，他没有看见过一只西班牙本地狗和我们的指示犬相像。

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At the present time, eminent breeders try by methodical selection, with a distinct object in view, to make a new strain or sub-breed, superior to anything existing in the country. But, for our purpose, a kind of Selection, which may be called Unconscious, and which results from every one trying to possess and breed from the best individual animals, is more important. Thus, a man who intends keeping pointers naturally tries to get as good dogs as he can, and afterwards breeds from his own best dogs, but he has no wish or expectation of permanently altering the breed. Nevertheless I cannot doubt that this process, continued during centuries, would improve and modify any breed, in the same way as Bakewell, Collins, etc., by this very same process, only carried on more methodically, did greatly modify, even during their own lifetimes, the forms and qualities of their cattle. Slow and insensible changes of this kind could never be recognised unless actual measurements or careful drawings of the breeds in question had been made long ago, which might serve for comparison. In some cases, however, unchanged or but little changed individuals of the same breed may be found in less civilised districts, where the breed has been less improved. There is reason to believe that King Charles’s spaniel has been unconsciously modified to a large extent since the time of that monarch. Some highly competent authorities are convinced that the setter is directly derived from the spaniel, and has probably been slowly altered from it. It is known that the English pointer has been greatly changed within the last century, and in this case the change has, it is believed, been chiefly effected by crosses with the fox-hound; but what concerns us is, that the change has been effected unconsciously and gradually, and yet so effectually, that, though the old Spanish pointer certainly came from Spain, Mr. Borrow has not seen, as I am informed by him, any native dog in Spain like our pointer.

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经过同样的选择程序和细心训练，全体英国赛马的体量和速度都已超过了亲种阿拉伯马，所以，依照古德伍德赛马的规则，阿拉伯马的载重量被照顾减轻了。斯潘塞勋爵等人曾经指出，英格兰的牛同先前养在国内的原种相比较，其重量和早熟性都大大增加了。把关于瘤鼻鸽、翻飞鸽旧论文中的各种论述，与现存于英国、印度、波斯的品种加以比较，我想，我们便可以清晰追踪出它们不被察觉地经过的各个阶段，从而达到和岩鸽如此大相径庭的地步。

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By a similar process of selection, and by careful training, the whole body of English racehorses have come to surpass in fleetness and size the parent Arab stock, so that the latter, by the regulations for the Goodwood Races, are favoured in the weights they carry. Lord Spencer and others have shown how the cattle of England have increased in weight and in early maturity, compared with the stock formerly kept in this country. By comparing the accounts given in old pigeon treatises of carriers and tumblers with these breeds as now existing in Britain, India, and Persia, we can, I think, clearly trace the stages through which they have insensibly passed, and come to differ so greatly from the rock-pigeon.

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尤亚特举了一个上好的例证，说明一种选择过程的效果，它可以被看作是无意识的选择，因为饲养者根本没有预期过的，甚至没有希望过的结果产生了，这就是说，产生了两个不同的品系。尤亚特先生说，巴克利（Buckley）先生和伯吉斯（Burgess）先生所养的两群莱斯特绵羊（Leicester sheep），“都是从贝克韦尔先生的原种纯正繁殖下来的，持续了五十多年。熟悉这一问题的任何人都根本不会怀疑，上述任何一个所有者曾任何一次脱离过贝克韦尔先生的羊群的纯粹血统，但是两位先生的绵羊彼此间的差异却很大，看起来就像不同的变种”。

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Youatt gives an excellent illustration of the effects of a course of selection, which may be considered as unconsciously followed, in so far that the breeders could never have expected or even have wished to have produced the result which ensued—namely, the production of two distinct strains. The two flocks of Leicester sheep kept by Mr. Buckley and Mr. Burgess, as Mr. Youatt remarks, “have been purely bred from the original stock of Mr. Bakewell for upwards of fifty years. There is not a suspicion existing in the mind of any one at all acquainted with the subject that the owner of either of them has deviated in any one instance from the pure blood of Mr. Bakewell’s flock, and yet the difference between the sheep possessed by these two gentlemen is so great that they have the appearance of being quite different varieties.”

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如果现在有一种未开化人，野蛮得很，从不顾及家畜后代的遗传性状，然而当他们遇到防不胜防的饥馑或其他不测时，还会把合乎任何特殊目的的对他们特别有用的动物小心保存下来。因此这样选取出来的动物比起劣等动物一般都会留下更多的后代；所以在这个个案中，便进行了一种无意识的选择。我们知道，连火地岛（Tierra del Fuego）的未开化人也重视动物，闹饥荒时他们甚至杀吃年老妇女，认为其价值比狗低。

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If there exist savages so barbarous as never to think of the inherited character of the offspring of their domestic animals, yet any one animal particularly useful to them, for any special purpose, would be carefully preserved during famines and other accidents, to which savages are so liable, and such choice animals would thus generally leave more offspring than the inferior ones; so that in this case there would be a kind of unconscious selection going on. We see the value set on animals even by the barbarians of Tierra del Fuego, by their killing and devouring their old women, in times of dearth, as of less value than their dogs.

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在植物方面，通过最优良个体的偶然保存可以进行同样的逐步改良过程；不论它们在最初出现时是否有足够的差异可列为独特的变种，也不论是否由于杂交把两个以上的物种或族混合在一起，这种过程都清晰可见。比起旧的变种或它们的亲种，改良就表现在现在所看到的诸如三色堇、蔷薇、天竺葵、大理花等植物的一些变种，在大小和美观方面都有增益。从来没有人会期望从野生植株的种子得到上等的三色堇或大理花。也没有人会期望从野生梨的种子培育出爽口的上等梨，但他可能把野生的瘦弱梨苗培育成良种，如果它本来是从果园砧木来的。梨在古代虽有栽培，但据普林尼的描述看，似乎果实品质极差。我曾看到园艺著作中对于园艺者的绝技表示惊叹，他们竟从如此低劣的材料里培育出如此优秀的结果。不过，这手艺无疑是简简单单的，就其最终结果来说，几乎都是无意识地进行的。这就在于永远是把最有名的变种拿来栽培，播种它的种子，碰巧有稍微好一些的变种出现时，便进行选择，如此这般，一直进行下去。但是，古代园艺者栽培所能得到的最好梨树时，却从未想到我们要吃到什么样的优良果实；尽管我们吃的佳果在某种很小程度上归功于他们，他们是自然而然地选择和保存了他们所能寻获的最优良变种。

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In plants the same gradual process of improvement, through the occasional preservation of the best individuals, whether or not sufficiently distinct to be ranked at their first appearance as distinct varieties, and whether or not two or more species or races have become blended together by crossing, may plainly be recognised in the increased size and beauty which we now see in the varieties of the heartsease, rose, pelargonium, dahlia, and other plants, when compared with the older varieties or with their parent-stocks. No one would ever expect to get a first-rate heartsease or dahlia from the seed of a wild plant. No one would expect to raise a first-rate melting pear from the seed of a wild pear, though he might succeed from a poor seedling growing wild, if it had come from a garden-stock. The pear, though cultivated in classical times, appears, from Pliny’s description, to have been a fruit of very inferior quality. I have seen great surprise expressed in horticultural works at the wonderful skill of gardeners, in having produced such splendid results from such poor materials; but the art, I cannot doubt, has been simple, and, as far as the final result is concerned, has been followed almost unconsciously. It has consisted in always cultivating the best known variety, sowing its seeds, and, when a slightly better variety has chanced to appear, selecting it, and so onwards. But the gardeners of the classical period, who cultivated the best pear they could procure, never thought what splendid fruit we should eat; though we owe our excellent fruit, in some small degree, to their having naturally chosen and preserved the best varieties they could anywhere find.

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我认为，栽培植物这样缓慢地和无意识地累积起来的大量变化，解释了以下的熟知事实，即在大批个案中，我们对于花园和菜园里栽培悠久的植物，已无法辨认，无从知道其野生原种。如果说我们大多数的植物改进或改变到现今于人类有用的标准需要数百年、数千年，那么就能理解，澳大利亚、好望角等未开化人所居住的地方，为什么都不能向我们提供一种值得栽培的植物。拥有如此丰富物种的这些地区，并非由于奇异的偶然而没有任何有用植物的原种，只是因为该地植物还没有经过连续选择改良，以达到像古文明国家的植物那样完善的水平。

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A large amount of change in our cultivated plants, thus slowly and unconsciously accumulated, explains, as I believe, the well-known fact, that in a vast number of cases we cannot recognise, and therefore do not know, the wild parent-stocks of the plants which have been longest cultivated in our flower and kitchen gardens. If it has taken centuries or thousands of years to improve or modify most of our plants up to their present standard of usefulness to man, we can understand how it is that neither Australia, the Cape of Good Hope, nor any other region inhabited by quite uncivilised man, has afforded us a single plant worth culture. It is not that these countries, so rich in species, do not by a strange chance possess the aboriginal stocks of any useful plants, but that the native plants have not been improved by continued selection up to a standard of perfection comparable with that given to the plants in countries anciently civilised.

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关于未开化人所养的家畜，有一点不可忽略，就是至少在某些季节里，几乎总要为吃食而斗争。在环境极其不同的两个地区，体质上或构造上微有差异的同种个体，在这一地区常常会比在另一地区日子好过些；这样，由于以后还要详述的“自然选择”的过程，便会形成两个亚品种。这或者可以部分说明某些作者说过的情况，也就是为什么未开化人所养的变种，比文明国度里所养的变种，具有更多的真种性状。

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In regard to the domestic animals kept by uncivilised man, it should not be overlooked that they almost always have to struggle for their own food, at least during certain seasons. And in two countries very differently circumstanced, individuals of the same species, having slightly different constitutions or structure, would often succeed better in the one country than in the other, and thus by a process of “natural selection,” as will hereafter be more fully explained, two sub-breeds might be formed. This, perhaps, partly explains what has been remarked by some authors, namely, that the varieties kept by savages have more of the character of species than the varieties kept in civilised countries.

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鉴于上述人工选择所起的重要作用，不言自明，家养族的构造或习性为什么会适应于人类的需要或爱好。我想，我们还能进一步理解，家养族为什么会屡屡出现异常的性状，为什么外部性状的差异如此巨大，而内部器官的差异却相对地如此微小。除了可以看得见的外部性状外，人类几乎不能选择，或只能极其困难地选择构造上的任何偏差；其实对内部器官是很少计较的。除非大自然首先在轻微程度上向人类提供一些变异，人类永远不能动手选择。除非看到一只鸽子在某种轻微程度上尾巴已出现异常发育，人不会去试育扇尾鸽；除非看到一只鸽子嗉囊尺寸已经有些异乎寻常，人也不会去试育球胸鸽；任何性状，在最初露面时越异常，就越能引起人的注意。但是，人类试育扇尾鸽这样的说法，在大多数情况下毫无疑问是完全不正确的。最初选择尾巴略大的鸽子的人，做梦也想不到经过长期连续的、半无意识、半循规蹈矩的选择之后，那只鸽子的后代会变成什么样子。所有扇尾鸽的始祖恐怕只有略微展开的十四支尾羽，就像今日的爪哇扇尾鸽那样，或者像其他品种的个体那样具有十七支尾羽。最初的球胸鸽嗉囊的膨胀程度也许并不比今日浮羽鸽食管上部为大，而所有养鸽者都不管浮羽鸽的这种习性，它不是这个品种的看点之一。

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On the view here given of the all-important part which selection by man has played, it becomes at once obvious, how it is that our domestic races show adaptation in their structure or in their habits to man’s wants or fancies. We can, I think, further understand the frequently abnormal character of our domestic races, and likewise their differences being so great in external characters and relatively so slight in internal parts or organs. Man can hardly select, or only with much difficulty, any deviation of structure excepting such as is externally visible; and indeed he rarely cares for what is internal. He can never act by selection, excepting on variations which are first given to him in some slight degree by nature. No man would ever try to make a fantail, till he saw a pigeon with a tail developed in some slight degree in an unusual manner, or a pouter till he saw a pigeon with a crop of somewhat unusual size; and the more abnormal or unusual any character was when it first appeared, the more likely it would be to catch his attention. But to use such an expression as trying to make a fantail, is, I have no doubt, in most cases, utterly incorrect. The man who first selected a pigeon with a slightly larger tail, never dreamed what the descendants of that pigeon would become through long-continued, partly unconscious and partly methodical selection. Perhaps the parent bird of all fantails had only fourteen tail-feathers somewhat expanded, like the present Java fantail, or like individuals of other and distinct breeds, in which as many as seventeen tail-feathers have been counted. Perhaps the first pouter-pigeon did not inflate its crop much more than the turbit now does the upper part of its oesophagus,—a habit which is disregarded by all fanciers, as it is not one of the points of the breed.

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不要以为只有构造上的某种大偏差才会引起养鸽者的注意，他能觉察极小的差异，而且人类本性就在于珍视自家财物的任何新奇点，哪怕是轻微的。决不可用若干品种已经固定后的现今价值标准，去评判以前对同一物种诸个体的任何轻微差异所给予的价值。我们知道鸽子现在还会发生许多轻微的变异，不过此等变异却被当作各品种的缺点或离开完善标准的偏差而舍弃。普通鹅没有产生过任何显著的变种；图卢兹（Toulouse）鹅和普通鹅只在颜色上有所不同，而颜色这种性状极不稳定，但近来却当作不同品种在家禽展览会上展览了。

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Nor let it be thought that some great deviation of structure would be necessary to catch the fancier’s eye: he perceives extremely small differences, and it is in human nature to value any novelty, however slight, in one’s own possession. Nor must the value which would formerly be set on any slight differences in the individuals of the same species, be judged of by the value which would now be set on them, after several breeds have once fairly been established. Many slight differences might, and indeed do now, arise amongst pigeons, which are rejected as faults or deviations from the standard of perfection of each breed. The common goose has not given rise to any marked varieties; hence the Thoulouse and the common breed, which differ only in colour, that most fleeting of characters, have lately been exhibited as distinct at our poultry-shows.

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我想，这些观点进一步解释了有时能注意到的事实——即我们对于任何家养品种的起源或历史一无所知。但是实际上，一个品种就好比语言里的一种方言一样，几乎无法说它有明确的起源。人保存了构造上微有偏差的个体加以繁育，或者格外小心地匹配优良动物从而改良它们，而改良的动物便慢慢地传播到邻近的地方去。但是它们尚无单独的名称，而且很少得到重视，所以它们的历史就遭到忽视。当通过同样的缓慢而逐渐的过程得到进一步改良的时候，它们将传播得更广，并且被承认是单独的有价值的种类，这时大概才首次得到一个地方名称。在半文明的国度里，交通不太发达，新亚种的传播过程是缓慢的，人们会慢慢了解它。一旦其价值点得到充分认识，我称之为无意识选择的原则就会一如既往地有助于慢慢添加这一品种的特性，什么特性都有可能；品种的盛衰依时尚而定，时多时寡；按居民的文明程度，此多彼少。但是，关于这种缓慢、飘忽不定、不易觉察的变化的记载，肯定很少有机会被保留下来。

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I think these views further explain what has sometimes been noticed—namely, that we know nothing about the origin or history of any of our domestic breeds. But, in fact, a breed, like a dialect of a language, can hardly be said to have had a definite origin. A man preserves and breeds from an individual with some slight deviation of structure, or takes more care than usual in matching his best animals and thus improves them, and the improved individuals slowly spread in the immediate neighbourhood. But as yet they will hardly have a distinct name, and from being only slightly valued, their history will be disregarded. When further improved by the same slow and gradual process, they will spread more widely, and will get recognised as something distinct and valuable, and will then probably first receive a provincial name. In semi-civilised countries, with little free communication, the spreading and knowledge of any new sub-breed will be a slow process. As soon as the points of value of the new sub-breed are once fully acknowledged, the principle, as I have called it, of unconscious selection will always tend,—perhaps more at one period than at another, as the breed rises or falls in fashion,—perhaps more in one district than in another, according to the state of civilisation of the inhabitants,—slowly to add to the characteristic features of the breed, whatever they may be. But the chance will be infinitely small of any record having been preserved of such slow, varying, and insensible changes.

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现在得稍微谈谈有利于或不利于人工选择力的情况。高度的变异性显然是有利的，选择的材料随便供给，有利于选择发生作用；并不是否认哪怕一点点个体差异也是充分够用的，只要极其细心，也能向着几乎任何所希望的方向积累起大量变异。但是，对人们显著有用的或合意的变异只是偶然出现，所以个体如果饲养得多，变异出现的机会也就大量增加。因此，数量是成功的关键。关于这一原则，马歇尔（Marshall）针对约克郡各地的绵羊说过：“因为绵羊一般为穷人所有，并且大部分只是小群圈养，所以从来不能改良。”与此相反，苗圃园艺师栽培着大量的同样植物，在培育有价值的新变种方面，一般远比业余者成功。在任何国家养育一个物种的大群个体，就需要被安置在有利的生活条件下，才能自由繁育。如果个体稀少，不管其品质怎样，一般都得让其全部繁育，这样就会有效地妨碍选择。但最重要的一点也许是，动植物对人类应该十分有用，人类必须高度重视其价值，以致对每个个体品质或构造上的最微小偏差都会给予密切注意。要是没有这样的注意，就会一事无成。我曾见到有人一本正经地指出，正好在园艺者开始注意草莓的时候，它开始变异了，真是极大的幸运。草莓自被栽培以来，无疑是经常发生变异的，只不过微小的变异不曾被注意罢了。然而，一旦园艺者选出一些个体植株，果实稍微大些，稍微早熟些，味道稍微好些，然后从它们培育出幼苗，再选出最好的幼苗进行繁育，于是（在少量种间杂交的辅助下），许多妙不可言的草莓变种就培育出来了。这就是近三四十年来所种植的草莓变种。

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I must now say a few words on the circumstances, favourable, or the reverse, to man’s power of selection. A high degree of variability is obviously favourable, as freely giving the materials for selection to work on; not that mere individual differences are not amply sufficient, with extreme care, to allow of the accumulation of a large amount of modification in almost any desired direction. But as variations manifestly useful or pleasing to man appear only occasionally, the chance of their appearance will be much increased by a large number of individuals being kept; and hence this comes to be of the highest importance to success. On this principle Marshall has remarked, with respect to the sheep of parts of Yorkshire, that “as they generally belong to poor people, and are mostly in small lots, they never can be improved.” On the other hand, nurserymen, from raising large stocks of the same plants, are generally far more successful than amateurs in getting new and valuable varieties. The keeping of a large number of individuals of a species in any country requires that the species should be placed under favourable conditions of life, so as to breed freely in that country. When the individuals of any species are scanty, all the individuals, whatever their quality may be, will generally be allowed to breed, and this will effectually prevent selection. But probably the most important point of all, is, that the animal or plant should be so highly useful to man, or so much valued by him, that the closest attention should be paid to even the slightest deviation in the qualities or structure of each individual. Unless such attention be paid nothing can be effected. I have seen it gravely remarked, that it was most fortunate that the strawberry began to vary just when gardeners began to attend closely to this plant. No doubt the strawberry had always varied since it was cultivated, but the slight varieties had been neglected. As soon, however, as gardeners picked out individual plants with slightly larger, earlier, or better fruit, and raised seedlings from them, and again picked out the best seedlings and bred from them, then, there appeared (aided by some crossing with distinct species) those many admirable varieties of the strawberry which have been raised during the last thirty or forty years.

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至于雌雄各异的动物，防杂交的难易程度是能否形成新族的重要因素——至少在已经放养其他族类的地方是如此。在这方面，圈地能起作用。居无定所的未开化人和开阔平原的居民拥有的同一物种很少超过一个品种。鸽子能终身配对，这对养鸽者大有便利，于是虽混养在一个鸽棚里，许多族还能保纯。这样的条件想必有利于新品种的改良和形成。补充一下，鸽子能大量快速繁殖，劣鸽可杀掉食用，自由淘汰。相反，猫有夜游的习性，无法配对，虽然妇女孩子喜爱，但很少看到独特的品种能长久保存；有时看到的那些独特品种，几乎都是从外国输入的，往往来自海岛。虽然我并不怀疑各种家养动物的变异有多有少，然而猫、驴、孔雀、鹅等的独特品种稀少或干脆没有，则主要归咎于选择未曾发挥作用：猫是由于难以配对；驴是由于只有穷人少量饲养，不重视其繁育；孔雀是由于不容易饲养，种群不大；鹅是由于只有两种用途价值，供食用和取羽毛，特别是由于鹅显示独特种类并不带来愉悦。

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In the case of animals with separate sexes, facility in preventing crosses is an important element of success in the formation of new races,—at least, in a country which is already stocked with other races. In this respect enclosure of the land plays a part. Wandering savages or the inhabitants of open plains rarely possess more than one breed of the same species. Pigeons can be mated for life, and this is a great convenience to the fancier, for thus many races may be kept true, though mingled in the same aviary; and this circumstance must have largely favoured the improvement and formation of new breeds. Pigeons, I may add, can be propagated in great numbers and at a very quick rate, and inferior birds may be freely rejected, as when killed they serve for food. On the other hand, cats, from their nocturnal rambling habits, cannot be matched, and, although so much valued by women and children, we hardly ever see a distinct breed kept up; such breeds as we do sometimes see are almost always imported from some other country, often from islands. Although I do not doubt that some domestic animals vary less than others, yet the rarity or absence of distinct breeds of the cat, the donkey, peacock, goose, etc., may be attributed in main part to selection not having been brought into play: in cats, from the difficulty in pairing them; in donkeys, from only a few being kept by poor people, and little attention paid to their breeding; in peacocks, from not being very easily reared and a large stock not kept; in geese, from being valuable only for two purposes, food and feathers, and more especially from no pleasure having been felt in the display of distinct breeds.

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现把有关家养族动植物的起源总结一下。我认为，生活条件作用于生殖系统，具有高度的重要性，能造成变异性。某些作者认为，对于所有生物，变异性在一切条件下都是与生俱来，是必然的可能性，这一点我并不苟同。变异性的效应由于遗传和返祖的不同程度而发生变化。变异性是由许多未知的法则所支配的，特别是相关生长法则。有的可以归因于生活条件的直接作用。有的必须归因于使用和不使用。于是，最终的结果便变得无限复杂了。在某些个案中，我并不怀疑，不同原种的杂交，在家养品种的起源上起了重要的作用。在任何地方，若干家养品种一经形成之后，偶然的杂交，辅之以选择，无疑对于新亚种的形成大有帮助；但对于动物和实生植物，依我看变种杂交的重要性就过分地夸张了。对于用插枝、芽接等方法进行暂时繁殖的植物，物种和变种杂交的重要性是极大的，因为栽培者在这里可以不必顾虑杂种和混种的极度变异性以及杂种的不育性；可是非实生植物的个案对于我们不重要，因为其耐久性只是暂时的。我认为，选择的累积作用，无论是按部就班迅速地进行的，还是无意识地缓慢而更有效地进行的，都超出这些变化原因之上，远远是最占优势的“力量”。

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To sum up on the origin of our Domestic Races of animals and plants. I believe that the conditions of life, from their action on the reproductive system, are so far of the highest importance as causing variability. I do not believe that variability is an inherent and necessary contingency, under all circumstances, with all organic beings, as some authors have thought. The effects of variability are modified by various degrees of inheritance and of reversion. Variability is governed by many unknown laws, more especially by that of correlation of growth. Something may be attributed to the direct action of the conditions of life. Something must be attributed to use and disuse. The final result is thus rendered infinitely complex. In some cases, I do not doubt that the intercrossing of species, aboriginally distinct, has played an important part in the origin of our domestic productions. When in any country several domestic breeds have once been established, their occasional intercrossing, with the aid of selection, has, no doubt, largely aided in the formation of new sub-breeds; but the importance of the crossing of varieties has, I believe, been greatly exaggerated, both in regard to animals and to those plants which are propagated by seed. In plants which are temporarily propagated by cuttings, buds, etc., the importance of the crossing both of distinct species and of varieties is immense; for the cultivator here quite disregards the extreme variability both of hybrids and mongrels, and the frequent sterility of hybrids; but the cases of plants not propagated by seed are of little importance to us, for their endurance is only temporary. Over all these causes of Change I am convinced that the accumulative action of Selection, whether applied methodically and more quickly, or unconsciously and more slowly, but more efficiently, is by far the predominant Power.

序号 英文/音标 中文解释 更多操作

Inheritance

[ɪn'herɪtəns]

n.遗传;遗产;继承;继承物

probability

[ˌprɒbə'bɪləti]

n.可能性

Knight

[naɪt]

n.骑士;爵士;武士

excess

[ɪk'ses]

n.超过;过量;过剩

cultivation

[ˌkʌltɪ'veɪʃn]

n.教化;培养;耕作

domesticate

[də'mestɪkeɪt]

vt.驯养;使专注于家务;教化

modification

[ˌmɒdɪfɪ'keɪʃn]

n.修改;修正;修饰

embryo

['embriəʊ]

n.胚胎;萌芽

unnatural

[ʌn'nætʃrəl]

adj.不自然的;反常的;不近人情的

reproductive

[ˌriːprə'dʌktɪv]

adj.复制的;生殖的

confinement

[kən'faɪnmənt]

n.拘禁;限制;分娩

susceptible

[sə'septəbl]

adj.易受外界影响的;易受感染的;容许…的

utmost

['ʌtməʊst]

adj.极度的;最大限度的

singular

['sɪŋɡjələ(r)]

a. 非凡的；卓越的;

reproduction

[ˌriːprə'dʌkʃn]

n.再现;生殖

tropic

['trɒpɪk]

n.回归线;热带

whereas

[ˌweər'æz]

conj.然而;鉴于

fertile

['fɜːtaɪl]

adj.肥沃的;富饶的;能繁殖的;多产的;(创造力)丰富的

pollen

['pɒlən]

n.花粉

utterly

['ʌtəli:]

adv.完全;全然;绝对

hybrid

['haɪbrɪd]

n.混合物;杂种;混血儿

sickly

['sɪkli]

adj.病弱的;令人作呕的;无精打采的

tameable

[teɪmə​bəl ]

可驯服的;

offspring

['ɒfsprɪŋ]

n.后代;子孙;产物

Sterility

[stə'rɪləti]

n.不生育;贫瘠

sterility

[stə'rɪləti]

n.不生育;贫瘠

domestication

[dəˌmestɪ'keɪʃn]

n.驯服;教化

propagate

['prɒpəɡeɪt]

v.繁殖;增殖;传播;传送

graft

[ɡrɑːft]

n.嫁接;移植

physiologist

[ˌfɪzi'ɒlədʒɪst]

n.生理学家

earliest

['ɜːliɪst]

n.最早

ovule

['ɒvjuːl]

n.胚珠;卵子

seedling

['siːdlɪŋ]

n.幼苗

litter

['lɪtə(r)]

n. 【U】杂乱物；废纸;

unimportant

[ˌʌnɪm'pɔːtnt]

adj.不重要的

inheritance

[ɪn'herɪtəns]

n.遗传;遗产;继承;继承物

moisture

['mɔɪstʃə(r)]

n.水分;潮气;湿度

thickness

['θɪknəs]

n.厚度;浓度;层

skeleton

['skelɪtn]

n.骨架;纲要;骨骼;骨瘦如柴的人或动物;家丑

udder

['ʌdə(r)]

n.(母牛、母山羊)乳房;乳腺

habitual

[hə'bɪtʃuəl]

adj.惯常的;习惯的

droop

[druːp]

v.低垂;下垂;(草木)枯萎;(精神)萎靡

disuse

[dɪs'juːs]

n.废止

dim

[dɪm]

adj.暗淡的;模糊的;笨的

allude

[ə'luːd]

v.暗示;暗指

larva

['lɑːvə]

n.幼虫;幼体

breeder

['briːdə(r)]

n.饲养动物的人;培育植物的人;【核】增殖(反应)堆

elongate

['iːlɒŋɡeɪt]

v.延长;伸长

invariably

[ɪn'veəriəbli]

adv.不变地;总是;一贯地

deaf

[def]

adj.聋的;充耳不闻的

peculiarity

[pɪˌkjuːli'ærəti]

n.特质;特性;怪癖;古怪

poison

['pɔɪzn]

n.毒药;毒害;败坏道德之事

imperfect

[ɪm'pɜːfɪkt]

adj.不完美的;有缺点的;未完善的

beak

[biːk]

n.鸟嘴;鸟嘴状物体;鹰钩鼻

augment

[ɔːɡ'ment]

vt.增加

infinite

['ɪnfɪnət]

adj.无穷的;无限的

diversify

[daɪ'vɜːsɪfaɪ]

vt.使多样化;使变化;使不同

treatise

['triːtɪs]

n.论文;论述;故事

physiological

[ˌfɪziə'lɒdʒɪkl]

adj.生理的;生理学的

deviation

[ˌdiːvi'eɪʃn]

n.偏离;出轨;背弃

reappear

[ˌriːə'pɪə(r)]

v.再出现

revert

[rɪ'vɜːt]

vi.恢复;回复;归还

earlier

['ɜːlɪə]

adj.早的;初期的

silkworm

['sɪlkwɜːm]

n.蚕

caterpillar

['kætəpɪlə(r)]

n. 【定语】履带式...;

reversion

[rɪ'vɜːʃn]

n.返回;逆转;恢复;反向

naturalist

['nætʃrəlɪst]

n.自然主义者;博物学者

gradual

['ɡrædʒuəl]

adj.逐渐的;逐步的;平缓的

deduction

[dɪ'dʌkʃn]

n.扣除;扣除额;推论;推理;演绎

ensue

[ɪn'sjuː]

v.跟着发生;继起;因而产生

intercross

[ˌɪntɜː'krɒs]

vt.使相互交叉

wholly

['həʊlli]

adv.完全地;全部地;一概

manifest

['mænɪfest]

vt.显示;证实;表露

genus

['dʒiːnəs]

n.【生物学】属;类;种;型

lesser

['lesə(r)]

adj.较少的;较小的;次要的

competent

['kɒmpɪtənt]

adj.有能力的;足够的;胜任的

descendant

[dɪ'sendənt]

n.后裔;子孙;后代

aboriginal

[ˌæbə'rɪdʒənl]

adj.原始的;土著的

perpetual

[pə'petʃuəl]

adj.永久的;永恒的;一再往复的

generic

[dʒə'nerɪk]

adj.一般的;普通的;共有的;没有商标的

valuation

[ˌvælju'eɪʃn]

n.评价;估价

empirical

[ɪm'pɪrɪkl]

adj.经验主义的;经验(上)的

inhabit

[ɪn'hæbɪt]

v.居住于;占据;栖息

manufacture

[ˌmænju'fæktʃə(r)]

v.(手工)制造

Nile

[naɪl]

n.尼罗河(非洲)

savage

['sævɪdʒ]

a. 野蛮的，未开化的;

hump

[hʌmp]

n.忧郁；烦恼;

fowl

[faʊl]

n.禽;禽肉

prototype

['prəʊtətaɪp]

n.原型;范例;雏形

converse

[kən'vɜːs]

n.相反的事物;逆命题

Hungary

['hʌŋɡəri]

n.匈牙利【欧洲】

Spain

[speɪn]

n. 西班牙【欧洲；首都马德里 Madrid】;

mongrel

['mʌŋɡrəl]

n.杂种狗;杂交动植物;混血儿

expressly

[ɪk'spresli]

adv.清楚地;特意地;专门地

utter

['ʌtə(r)]

adj.完全的;全然的;绝对的

kindly

['kaɪndli]

adj.和蔼的;温和的;爽快的

honorable

['ɒnərəbl]

adj.光荣的;可敬的;体面的.

eminent

['emɪnənt]

adj.著名的;卓越的

tumbler

['tʌmblə(r)]

n.不倒翁;杂技演员;平底无脚酒杯;锁的制动栓

eyelid

['aɪlɪd]

n.眼皮;眼睑

orifice

['ɒrɪfɪs]

n.孔

nostril

['nɒstrəl]

n.鼻孔

tumble

['tʌmbl]

v.暴跌;倒塌;跌倒;翻滚;弄乱;明白;突然发现

runt

[rʌnt]

n.小家畜;小矮子

inflate

[ɪn'fleɪt]

vt.使膨胀;使得意;使通货膨胀

excite

[ɪk'saɪt]

vt.使兴奋;使激动;刺激;激起

continual

[kən'tɪnjuəl]

adj.不断的;频繁的;连续的

hood

[hʊd]

n.头巾;兜帽;遮罩;引擎盖

proportional

[prə'pɔːʃənl]

adj.成比例的;相称的

abort

[ə'bɔːt]

v.流产;堕胎;中止

curvature

['kɜːvətʃə(r)]

n.弯曲;(几何)曲率

ramus

['reɪməs]

n.【生】分支;【解】岔枝

sacral

['seɪkrəl]

adj.骶骨的;圣礼的;宗教仪式的

vertebra

['vɜːtɪbrə]

n.脊椎骨;椎骨

aperture

['æpətʃə(r)]

n.孔;孔径

width

[wɪdθ]

n.宽度;广度

nestle

['nesl]

v.依偎;(舒适地)安顿

clothe

[kləʊð]

vt.穿上;赋予

hatch

[hætʃ]

n.孵化;舱口，舱口盖

disposition

[ˌdɪspə'zɪʃn]

n.性情;倾向;安排;处置;控制;【计算机】 配置情况

applicable

[ə'plɪkəbl]

adj.合适的

perch

[pɜːtʃ]

n.栖木;高位;杆;河鲈鱼

extinct

[ɪk'stɪŋkt]

adj.灭绝的;熄灭的;消亡的

precipice

['presəpɪs]

n.断崖;绝壁;险境

flier

['flaɪə]

n.飞行员;飞行物;飞机上的乘客;传单;投机.

exterminate

[ɪk'stɜːmɪneɪt]

vt.消灭;扑灭;根绝

islet

['aɪlət]

n.小岛

Mediterranean

[ˌmedɪtə'reɪniən]

adj.地中海的

rash

[ræʃ]

n.疹子;大量

thorough

['θʌrə]

adj.彻底的;完全的;详尽的;细致深入的

abnormal

[æb'nɔːml]

adj.反常的;不正常的

pick

[pɪkt]

采摘，挑选；

fantail

['fænteɪl]

n.扇状尾;扇尾鸽

barb

[bɑːb]

n.倒钩;刻薄的言语

mottle

['mɒtl]

vt.使成杂色;弄成斑驳

countenance

['kaʊntənəns]

n.面容;面部表情;支持

indefinite

[ɪn'defɪnət]

adj.模糊的;不确定的;无限期的

confound

[kən'faʊnd]

vt.使困惑;混淆;挫败;诅咒

inter

[ɪn'tɜː(r)]

vt.埋葬

dynasty

['dɪnəsti]

n.朝代;王朝

Birch

[bɜːtʃ]

n.桦树;桦木;用桦条抽打

bill

[bɪl]

①帐单；清单;

monarch

['mɒnək]

n.帝王;君主

Iran

[ɪ'rɑːn]

n.伊朗

astonishingly

[ə'stɒnɪʃɪŋli]

adv.惊人地;异常地

felted

['feltɪd]

v. 把 ... 制成毡(使 ... 粘结)

finch

[fɪntʃ]

n.雀类

cultivator

['kʌltɪveɪtə(r)]

n.耕种者;耕耘机

raiser

['reɪzə]

n.提高者;饲养者;栽培者;筹集者

disbelieve

[ˌdɪsbɪ'liːv]

v.不信;怀疑

descent

[dɪ'sent]

n.下降;下坡;家世;血统;侵袭;衰落;继承

caution

['kɔːʃn]

n.警告;慎重;戒备;吸引人眼球的人或物

adaptation

[ˌædæp'teɪʃn]

n.改编;改编成的作品;适应;【心】(感官)适应，适应性变化

fancy

['fænsi]

n. 【C】设想；幻想；空想;

botanist

['bɒtənɪst]

n.植物学家

pasture

['pɑːstʃə(r)]

n.牧场;草原

wool

[wʊl]

n.羊毛;绒线

orchard

['ɔːtʃəd]

n.果园

accumulative

[ə'kjuːmjələtɪv]

adj.积聚的;累计的

hypothetical

[ˌhaɪpə'θetɪkl]

adj.假设的;假定的

acquaint

[ə'kweɪnt]

vt.使了解;使熟知;告知

agriculturist

[ˌægrɪ'kʌltʃərɪst]

n.农业家;农业技师

mould

[məʊld]

n.发霉;模具

skilful

['skɪlfl]

adj.熟练的;巧妙的;技术好的.

horticulturist

[hɔːtɪˈkʌlʧərɪst]

n.园艺家

florist

['flɒrɪst]

n.花商，花店;种花人

pod

[pɒd]

n.豆荚;分离舱

tuber

['tjuːbə(r)]

n.块茎;球根;【解】结节;隆起;肿胀

gooseberry

['ɡʊzbəri]

n.醋栗树;醋栗;不知趣的第三者

chiefly

['tʃiːfli]

adv.主要地

scarcely

['skeəsli]

adv.几乎不;简直不;刚刚;决不

acknowledgement

[ək'nɒlɪdʒmənt]

n.承认;确认;感谢.

rude

[ruːd]

adj.粗鲁无礼的;原始的;未加工的;粗糙的;猛烈的

exportation

[ˌekspɔː'teɪʃn]

n.出口

Genesis

['dʒenəsɪs]

n.起源;发生

attest

[ə'test]

v.证明;作证

Africa

['æfrɪkə]

n.非洲

Negro

['niːɡrəʊ]

adj.黑人的

pointer

['pɔɪntə(r)]

n.指针;教鞭;(能指出猎物位置的)猎犬;暗示;主意

methodical

[mə'θɒdɪkl]

adj.有条不紊的;井然的

Spencer

['spensə]

n.(羊毛)短上衣;Spencer.斯宾塞(姓氏;男子名).

deviate

['diːvieɪt]

v.偏离;脱离

famine

['fæmɪn]

n.饥荒;极度缺乏

liable

['laɪəbl]

a. 有(法律)责任的；有义务的;

inferior

[ɪn'fɪəriə(r)]

adj.下级的

barbarian

[bɑː'beəriən]

n.野蛮人

devour

[dɪ'vaʊə(r)]

v.吞食;毁灭;贪婪地阅读

preservation

[ˌprezə'veɪʃn]

n.保存

sow

[saʊ]

v.播种;散布

usefulness

['juːsfəlnəs]

n.有用;有用性

Cape

[keɪp]

n.岬;海角

disregard

[ˌdɪsrɪ'ɡɑːd]

vt.不顾;忽视

dialect

['daɪəlekt]

n.方言;地方话

provincial

[prə'vɪnʃl]

adj.省的;地方的;偏狭的

amateur

['æmətə(r)]

n.外行;业余爱好者

fortunate

['fɔːtʃənət]

adj.幸运的;侥幸的;带来幸运的

strawberry

['strɔːbəri]

n.草莓

enclosure

[ɪn'kləʊʒə(r)]

n.附件;围墙;围绕

mingle

['mɪŋɡl]

vt.使混合;使结合

nocturnal

[nɒk'tɜːnl]

adj.在夜间的;(指生物)夜间活动的

peacock

['piːkɒk]

n.(雄)孔雀;爱炫耀的人

predominant

[prɪ'dɒmɪnənt]

adj.主要的;占优势的;显著的

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