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物种起源|The Origin of Species

第三章　生存斗争|CHAPTER III　STRUGGLE FOR EXISTENCE

属类： 双语小说 【分类】其他读物 阅读：[7137]
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对自然选择的影响——该术语的广义——几何级数的增加——归化动植物的迅速增加——抑制增加的性质——竞争的普遍性——气候的影响——个体数目的保护——全体动植物在自然界的复杂关系——同种的个体和变种间生存斗争最剧烈；同属的物种间也往往剧烈——生物与生物的关系是一切关系中最重要的

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Bears on natural selection—The term used in a wide sense— Geometrical powers of increase—Rapid increase of naturalised animals and plants—Nature of the checks to increase—Competition universal—Effects of climate—Protection from the number of individuals—Complex relations of all animals and plants throughout nature—Struggle for life most severe between individuals and varieties of the same species; often severe between species of the same genus—The relation of organism to organism the most important of all relations

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进入本章的主题之前，必须先说几句开场白，表明生存斗争对于“自然选择”的影响。前一章已经谈到，自然状况下的生物是有个体变异的；这一点从未听说有争论。把一群存疑类型叫作物种、亚种或变种，对于我们无关紧要。例如，只要承认有显著变种存在，把英国植物中二三百个存疑类型列入哪一级都没有关系。但是，仅仅有个体变异和少数显著变种的存在，虽然为本书打基础是必要的，但很少能够帮我们理解物种在自然状况下是怎样发生的。体制的这一部分对于另一部分及其对于生活条件的一切巧妙适应，生物之间的一切巧妙适应，是怎样完善的呢？在啄木鸟和槲寄生身上，我们明显看到了这种美妙的相互适应；在依附兽毛、羽毛之上的最下等寄生物上，在潜水甲虫的构造上，在微风中飘荡的冠毛种子上，也差不多同样明显；简而言之，无论何地和生物界的每一部分，都能看到美妙的适应。

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Before entering on the subject of this chapter, I must make a few preliminary remarks, to show how the struggle for existence bears on Natural Selection. It has been seen in the last chapter that amongst organic beings in a state of nature there is some individual variability; indeed I am not aware that this has ever been disputed. It is immaterial for us whether a multitude of doubtful forms be called species or sub-species or varieties; what rank, for instance, the two or three hundred doubtful forms of British plants are entitled to hold, if the existence of any well-marked varieties be admitted. But the mere existence of individual variability and of some few well-marked varieties, though necessary as the foundation for the work, helps us but little in understanding how species arise in nature. How have all those exquisite adaptations of one part of the organisation to another part, and to the conditions of life, and of one distinct organic being to another being, been perfected? We see these beautiful co-adaptations most plainly in the woodpecker and missletoe; and only a little less plainly in the humblest parasite which clings to the hairs of a quadruped or feathers of a bird; in the structure of the beetle which dives through the water; in the plumed seed which is wafted by the gentlest breeze; in short, we see beautiful adaptations everywhere and in every part of the organic world.

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不妨再问一下，变种即我所谓的初始物种，最终怎样变成货真价实的物种了呢？在大多数情形下，物种间的差异，显然远远超过了同一物种的变种间的差异。那些组成所谓属的种群间的差异比同属物种间的差异为大，这些种群是怎样发生的呢？所有这些结果都不可避免地是从生存斗争中得来的，下一章将充分论述。由于生存斗争，变异无论多么轻微，无论由于什么原因发生，只要任何物种的个体在与其他生物、与自然界的无限复杂关系中多少从中得益，就会倾向于保存该个体，并且一般会让后代继承下来。后代也因此有了较好的生存机会，因为任何物种间歇性产生的许多个体，只有少数能够生存。我把保存每一个有用的微小变异的这一原则称为“自然选择”，表明它和人工选择力的关系。我们已经看到，人类利用选择，确能产生伟大的结果，并且通过累积自然之手所给予的微小而有用的变异，能使生物适合于自己的用途。但是我们以后将看到，自然选择是一种不断随时激活的力量，它无比地优越于微弱的人力。天工无限优于人工。

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Again, it may be asked, how is it that varieties, which I have called incipient species, become ultimately converted into good and distinct species, which in most cases obviously differ from each other far more than do the varieties of the same species? How do those groups of species, which constitute what are called distinct genera, and which differ from each other more than do the species of the same genus, arise? All these results, as we shall more fully see in the next chapter, follow inevitably from the struggle for life. Owing to this struggle for life, any variation, however slight and from whatever cause proceeding, if it be in any degree profitable to an individual of any species, in its infinitely complex relations to other organic beings and to external nature, will tend to the preservation of that individual, and will generally be inherited by its offspring. The offspring, also, will thus have a better chance of surviving, for, of the many individuals of any species which are periodically born, but a small number can survive. I have called this principle, by which each slight variation, if useful, is preserved, by the term of Natural Selection, in order to mark its relation to man’s power of selection. We have seen that man by selection can certainly produce great results, and can adapt organic beings to his own uses, through the accumulation of slight but useful variations, given to him by the hand of Nature. But Natural Selection, as we shall hereafter see, is a power incessantly ready for action, and is as immeasurably superior to man’s feeble efforts, as the works of Nature are to those of Art.

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现在就生存斗争稍加详论。我以后的著作还要大事讨论这个问题，完全值得讨论。老德康多尔和赖尔已经富于哲理性地阐明了，一切生物都暴露在剧烈的竞争之中。关于植物，曼彻斯特区监督牧师赫伯特（W. Herbert）以无人能及的气魄和才华进行了讨论，显然来源于渊博的园艺学知识。口头上承认生存斗争的普遍性，是再容易不过的事情，但至少我认为，对这一结论要念念不忘却难上加难。然而，我认为，除非在思想上彻底体会这一点，否则我们对于包含着分布、稀少、繁盛、灭绝以及变异等各种事实的整个自然系统，就是认识模糊或完全误解。我们看见自然界的外貌喜气洋洋，我们常常看见食物过剩，却看不见或者忘却安闲地在周围唱歌的鸟，多数是以昆虫或种子为生的，因而经常性地在毁灭生命。我们会忘记这些鸣禽，它们的蛋或幼鸟，会被猛禽猛兽所大批毁灭。我们并非总是记得，食物虽然现在是过剩的，但并不见得每年的所有季节都是这样。

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We will now discuss in a little more detail the struggle for existence. In my future work this subject shall be treated, as it well deserves, at much greater length. The elder De Candolle and Lyell have largely and philosophically shown that all organic beings are exposed to severe competition. In regard to plants, no one has treated this subject with more spirit and ability than W. Herbert, Dean of Manchester, evidently the result of his great horticultural knowledge. Nothing is easier than to admit in words the truth of the universal struggle for life, or more difficult—at least I have found it so—than constantly to bear this conclusion in mind. Yet unless it be thoroughly engrained in the mind, I am convinced that the whole economy of nature, with every fact on distribution, rarity, abundance, extinction, and variation, will be dimly seen or quite misunderstood. We behold the face of nature bright with gladness, we often see superabundance of food; we do not see, or we forget, that the birds which are idly singing round us mostly live on insects or seeds, and are thus constantly destroying life; or we forget how largely these songsters, or their eggs, or their nestlings, are destroyed by birds and beasts of prey; we do not always bear in mind, that though food may be now superabundant, it is not so at all seasons of each recurring year.

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应当先设定，术语生存斗争采取广义的比喻义，包含生物的相互依存关系，更重要的，不仅仅是个体保命且成功留下后代。两只狗类动物在饥饿的时候，为了生存争食，可以说实实在在在互相搏斗。但是，生长在沙漠边缘的植物，可以说是在抗旱求生存，但适当地应该说，它是依存于潮气。一株植物，每年结一千粒种子，但平均只有一粒能成熟结籽，可以确切地说，它是在和覆被地面的同类和异类植物做斗争。槲寄生依存于苹果树和少数其他树木，但只能牵强附会地说它在和这些树木做斗争，一株树上这种寄生物过多会枯死。但是如果几株槲寄生苗密集地寄生在同一枝条上，就可以实实在在地说是在互相斗争。槲寄生是由鸟类散布的，所以生存便取决于鸟类；可以比喻地说，为了引诱鸟类来吞吃果实从而散布种子，就是在和其他结籽植物做斗争了。在这几种彼此交叉的意义中，我出于方便，采用了生存斗争这一通用术语。

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I should premise that I use the term Struggle for Existence in a large and metaphorical sense, including dependence of one being on another, and including (which is more important) not only the life of the individual, but success in leaving progeny. Two canine animals in a time of dearth, may be truly said to struggle with each other which shall get food and live. But a plant on the edge of a desert is said to struggle for life against the drought, though more properly it should be said to be dependent on the moisture. A plant which annually produces a thousand seeds, of which on an average only one comes to maturity, may be more truly said to struggle with the plants of the same and other kinds which already clothe the ground. The missletoe is dependent on the apple and a few other trees, but can only in a far-fetched sense be said to struggle with these trees, for if too many of these parasites grow on the same tree, it will languish and die. But several seedling missletoes, growing close together on the same branch, may more truly be said to struggle with each other. As the missletoe is disseminated by birds, its existence depends on birds; and it may metaphorically be said to struggle with other fruit-bearing plants, in order to tempt birds to devour and thus disseminate its seeds rather than those of other plants. In these several senses, which pass into each other, I use for convenience sake the general term of struggle for existence.

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所有生物都有高速增殖的倾向，生存斗争不可避免。各种生物在其自然寿命中都会产生若干卵或种子，在生命的某一时期，某一季节，或者某一年，必定要遭到毁灭，否则按照几何级数增加的原则，数量就会很快多得泛滥，没有地方能够容纳。因此，由于产生的个体比能生存的多，无论如何一定会发生生存斗争，或者同种个体之间，或者同异种的个体斗争，或者同外界的生活条件斗争。这是马尔萨斯学说成倍地应用于整个的动植物界；在这种情形下，既不能人为地增加食物，也不能谨慎地限制交配。虽然某些物种现在可以或快或慢地增加数目，但是所有的物种并不能这样，因为世界容纳不下它们。

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A struggle for existence inevitably follows from the high rate at which all organic beings tend to increase. Every being, which during its natural lifetime produces several eggs or seeds, must suffer destruction during some period of its life, and during some season or occasional year, otherwise, on the principle of geometrical increase, its numbers would quickly become so inordinately great that no country could support the product. Hence, as more individuals are produced than can possibly survive, there must in every case be a struggle for existence, either one individual with another of the same species, or with the individuals of distinct species, or with the physical conditions of life. It is the doctrine of Malthus applied with manifold force to the whole animal and vegetable kingdoms; for in this case there can be no artificial increase of food, and no prudential restraint from marriage. Although some species may be now increasing, more or less rapidly, in numbers, all cannot do so, for the world would not hold them.

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毫无例外，各种生物都自然地高速增殖，如果不加以毁灭，一对生物的后代很快就会充满这个地球。即使生殖缓慢的人类，也在二十五年间增加了一倍，照此速率类推，几千年以后，后代就没有立足之地了。林奈（Linnaeus）计算过，如果一株一年生的植物只结两粒种子（生殖力这样低的植物是没有的），幼株翌年也只结两粒种子，这样下去，二十年后就会有一百万株了。大象在所有已知的动物中可谓是生殖最慢的，我曾费力去计算它在自然增殖方面最小的可能速率；可以保守地假定，它在三十岁开始生育，直到九十岁，在这期间共生三对小象；如果这样，五百年以后就会有一千五百万只象生存，都是第一对的后裔。

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There is no exception to the rule that every organic being naturally increases at so high a rate, that if not destroyed, the earth would soon be covered by the progeny of a single pair. Even slow-breeding man has doubled in twenty-five years, and at this rate, in a few thousand years, there would literally not be standing room for his progeny. Linnaeus has calculated that if an annual plant produced only two seeds—and there is no plant so unproductive as this—and their seedlings next year produced two, and so on, then in twenty years there would be a million plants. The elephant is reckoned to be the slowest breeder of all known animals, and I have taken some pains to estimate its probable minimum rate of natural increase: it will be under the mark to assume that it breeds when thirty years old, and goes on breeding till ninety years old, bringing forth three pair of young in this interval; if this be so, at the end of the fifth century there would be alive fifteen million elephants, descended from the first pair.

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但是，这个问题除了理论计算外，还有更好的证据；大量记载事例表明，自然状况下的各种动物如遇环境连续两三季都适宜的话，便会神速增殖。还有更触目惊心的证据，来自世界若干地方已返归野生状态的许多种类的家畜：生育慢的马和牛在南美洲以及近年来在澳洲的增殖率记录，若非确有实据，实难以置信。植物也是这样，以外地移入的植物为例，不到十年时间，就布满了全岛。现在阿根廷拉普拉塔（La Plata）广大平原上最普通的若干种植物，原来是欧洲引进的，可以密布数里格（1里格＝3平方英里）的地面上，几乎排除了一切他种植物。还有，我听福尔克纳（Falconer）博士说，在美洲发现后从那里移入到印度的一些植物，已从科摩林角（Cape Comorin）分布到喜马拉雅了。这些例子真是不胜枚举。在这些个案中，没有人假定这些动植物的能育性突如其来暂时地明显增加了。解释不言而喻，生活条件是十分适宜的，结果，老幼动植物的毁灭减少了，几乎所有新生者都能生育。结果按几何级数增殖，令人瞠目结舌，这干脆地说明了归化动植物在新家为什么会神速增殖和广泛散布。

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But we have better evidence on this subject than mere theoretical calculations, namely, the numerous recorded cases of the astonishingly rapid increase of various animals in a state of nature, when circumstances have been favourable to them during two or three following seasons. Still more striking is the evidence from our domestic animals of many kinds which have run wild in several parts of the world: if the statements of the rate of increase of slow-breeding cattle and horses in South America, and latterly in Australia, had not been well authenticated, they would have been quite incredible. So it is with plants: cases could be given of introduced plants which have become common throughout whole islands in a period of less than ten years. Several of the plants now most numerous over the wide plains of La Plata, clothing square leagues of surface almost to the exclusion of all other plants, have been introduced from Europe; and there are plants which now range in India, as I hear from Dr. Falconer, from Cape Comorin to the Himalaya, which have been imported from America since its discovery. In such cases, and endless instances could be given, no one supposes that the fertility of these animals or plants has been suddenly and temporarily increased in any sensible degree. The obvious explanation is that the conditions of life have been very favourable, and that there has consequently been less destruction of the old and young, and that nearly all the young have been enabled to breed. In such cases the geometrical ratio of increase, the result of which never fails to be surprising, simply explains the extraordinarily rapid increase and wide diffusion of naturalised productions in their new homes.

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自然状况下，几乎每一植株都产生种子，而动物很少不是每年交配的。因此我们可以断定，一切动植物都有几何级数增殖的倾向，凡是能生存下去的地方，每一处都要迅速满员，而几何级数增加的倾向必须在生命某一时期加以毁灭抑制。我想，对大家畜熟门熟路，会把我们引入歧途，对大量毁灭视而不见，也就忘记了每年有成千上万家畜遭屠宰食用，而且在自然状况下好歹也得有相等的数目消灭掉。

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In a state of nature almost every plant produces seed, and amongst animals there are very few which do not annually pair. Hence we may confidently assert, that all plants and animals are tending to increase at a geometrical ratio, that all would most rapidly stock every station in which they could any how exist, and that the geometrical tendency to increase must be checked by destruction at some period of life. Our familiarity with the larger domestic animals tends, I think, to mislead us: we see no great destruction falling on them, and we forget that thousands are annually slaughtered for food, and that in a state of nature an equal number would have somehow to be disposed of.

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生物有每年生产成千上万枚卵或种子的，也有只生产极少数卵或种子的，两者仅有的差别是，生殖慢的生物，在适宜的条件下需要稍稍长一些年限去布满整个地区，哪怕地方很大很大。神鹰（condor）产两三枚卵，鸵鸟（ostrich）产二三十个卵，然而在同一地区，神鹰可能为数更多；管鼻鹱（Fulmar petrel）只产一枚卵，但公认是世界上最多的鸟。一种蝇产卵成百上千，另一种蝇，如虱蝇（hippobosca）只产一枚卵；但生卵数量多少，并不能决定两个物种在一个地区内可以养活多少个体。所依赖的食物大起大落的物种，多产卵是较重要的，因为可以迅速增殖。但是大量产卵或种子的真正重要性，却在于补偿生命某一阶段的大量毁灭；大多数情况下这个阶段就是初始期。如果一头动物好歹能保护住卵或幼仔，少量生产仍然能充分保持平均数量；如果卵或幼仔遭到大量毁灭，就必须大量生产，否则物种就要灭绝，假如有一种树平均能活一千年，哪怕千年产一粒种，假定种子不毁，又能保证在适宜的地方萌发，这就足以保持这种树的数目了。所以在所有情况下，任何动植物，平均数目只间接地取决于卵或种子的数目。

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The only difference between organisms which annually produce eggs or seeds by the thousand, and those which produce extremely few, is, that the slow-breeders would require a few more years to people, under favourable conditions, a whole district, let it be ever so large. The condor lays a couple of eggs and the ostrich a score, and yet in the same country the condor may be the more numerous of the two: the Fulmar petrel lays but one egg, yet it is believed to be the most numerous bird in the world. One fly deposits hundreds of eggs, and another, like the hippobosca, a single one; but this difference does not determine how many individuals of the two species can be supported in a district. A large number of eggs is of some importance to those species, which depend on a rapidly fluctuating amount of food, for it allows them rapidly to increase in number. But the real importance of a large number of eggs or seeds is to make up for much destruction at some period of life; and this period in the great majority of cases is an early one. If an animal can in any way protect its own eggs or young, a small number may be produced, and yet the average stock be fully kept up; but if many eggs or young are destroyed, many must be produced, or the species will become extinct. It would suffice to keep up the full number of a tree, which lived on an average for a thousand years, if a single seed were produced once in a thousand years, supposing that this seed were never destroyed, and could be ensured to germinate in a fitting place. So that in all cases, the average number of any animal or plant depends only indirectly on the number of its eggs or seeds.

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观察大自然的时候，千万记住上述论点，千万不要忘记周围每一个生物可以说都在竭力增殖，每一种生物在生命的某一时期要靠斗争而生活；千万不要忘记在每一世代或者间隔几代，大毁灭不可避免地要降临幼者或老者。只要少许减轻抑制作用，只要缓和毁灭，物种的数量几乎立刻就会大事增加。大自然的面孔可以比作高产的表面，密密麻麻打入了万千尖利的楔子，不停地击打向内插，有时候击打一根楔子，然后加大力气击打另一根。

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In looking at Nature, it is most necessary to keep the foregoing considerations always in mind—never to forget that every single organic being around us may be said to be striving to the utmost to increase in numbers; that each lives by a struggle at some period of its life; that heavy destruction inevitably falls either on the young or old, during each generation or at recurrent intervals. Lighten any check, mitigate the destruction ever so little, and the number of the species will almost instantaneously increase to any amount. The face of Nature may be compared to a yielding surface, with ten thousand sharp wedges packed close together and driven inwards by incessant blows, sometimes one wedge being struck, and then another with greater force.

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各个物种有增殖的自然倾向，其抑制因素极其含糊。看一看最生机勃勃的物种，其数量越是密密匝匝，进一步增殖的倾向也越强。抑制增殖的因素究竟是什么，我们连一个事例也弄不明白。这也不足为怪，只要想一想，我们在这方面是何等无知，哪怕对于远比任何其他动物更了解的人类也是如此。这一主题已有若干作者高论过了，我期望将来在自己的著作里详论抑制增殖的因素，特别是对于南美洲的野生动物。这里我只稍微谈一谈，让读者注意几个要点。卵或幼小动物一般看起来受害最多，但不能一概而论。植物的种子被毁的极多，但从我所做的某些观察得知，在已布满他种植物的土地上发芽时，幼苗受害最多。幼苗还会被各种敌害大量毁灭。例如，有一块三英尺长二英尺宽的土地，翻耕除草后，不会再受其他植物的抑制，土著杂草出秧时，我在所有幼苗上做了记号，357株中，不下295株毁灭了，主要是蛞蝓、昆虫吃掉了。在长期修剪的草皮，四脚兽细嚼慢咽过的草皮也一样，如果让草任意生长，强壮的植物会逐渐灭掉不强的，哪怕后者已经长大。例如在一小块草皮（三英尺乘四英尺）上生长着二十个物种，其中九个物种由于其他物种的自由生长而死亡了。

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What checks the natural tendency of each species to increase in number is most obscure. Look at the most vigorous species; by as much as it swarms in numbers, by so much will its tendency to increase be still further increased. We know not exactly what the checks are in even one single instance. Nor will this surprise any one who reflects how ignorant we are on this head, even in regard to mankind, so incomparably better known than any other animal. This subject has been ably treated by several authors, and I shall, in my future work, discuss some of the checks at considerable length, more especially in regard to the feral animals of South America. Here I will make only a few remarks, just to recall to the reader’s mind some of the chief points. Eggs or very young animals seem generally to suffer most, but this is not invariably the case. With plants there is a vast destruction of seeds, but, from some observations which I have made, I believe that it is the seedlings which suffer most from germinating in ground already thickly stocked with other plants. Seedlings, also, are destroyed in vast numbers by various enemies; for instance, on a piece of ground three feet long and two wide, dug and cleared, and where there could be no choking from other plants, I marked all the seedlings of our native weeds as they came up, and out of the 357 no less than 295 were destroyed, chiefly by slugs and insects. If turf which has long been mown, and the case would be the same with turf closely browsed by quadrupeds, be let to grow, the more vigorous plants gradually kill the less vigorous, though fully grown, plants: thus out of twenty species growing on a little plot of turf (three feet by four) nine species perished from the other species being allowed to grow up freely.

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每个物种所能吃到的食物数量，当然为各物种的增殖划了极限；但决定一个物种的平均数量，往往不在于获得食物，而在于他种动物的捕食。例如，似乎很少有人怀疑，任何大庄园的鹧鸪、松鸡、野兔的数量主要决定于有害兽的消灭。如果今后二十年中英格兰不射杀一个猎物，同时也不消灭有害兽，那么猎物很有可能比现在还要来得少，虽然现在每年要射杀百十万只。相反，在某些情形下，例如象和河马，是不会被食肉兽捕杀的；在印度甚至老虎也极少敢于攻击母象保护下的小象。

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The amount of food for each species of course gives the extreme limit to which each can increase; but very frequently it is not the obtaining food, but the serving as prey to other animals, which determines the average numbers of a species. Thus, there seems to be little doubt that the stock of partridges, grouse, and hares on any large estate depends chiefly on the destruction of vermin. If not one head of game were shot during the next twenty years in England, and, at the same time, if no vermin were destroyed, there would, in all probability, be less game than at present, although hundreds of thousands of game animals are now annually killed. On the other hand, in some cases, as with the elephant and rhinoceros, none are destroyed by beasts of prey: even the tiger in India most rarely dares to attack a young elephant protected by its dam.

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决定物种的平均数量，气候至关重要，我认为极端寒冷或干旱季节的不时出现，是最有效的抑制因素。我估算过，1854—1855年冬季，我的居住地消灭的鸟类达五分之四；这真是重大的毁灭，我们知道，如果人类因传染病而死去百分之十，便是惨重的死亡率了。气候的作用乍看似乎同生存斗争无关，而由于气候的主要作用在于减少食物，便引发了同种、异种的个体间最激烈的斗争，因为它们靠同样食物生存。哪怕是气候，例如严寒直接发生作用时，受害最大的还是最不健壮的个体，或者入冬后获得食物最少的个体。我们从南往北走，或从湿润地区到干燥地区，必定会看出某些物种渐次稀少，最后绝迹。气候变化显而易见，我们不免把这整个的效果归因于它的直接作用。但这种见解大错特错了，我们忘记了，各个物种即使在其最繁盛的地方，也经常在生命的某一时期由于敌害或同一地方同一食物的竞争者而大量毁灭。只要气候有轻微变化而稍有利于这些敌害或竞争者，它们便会增殖；由于各个地区都已布满了生物，其他物种便要减少。我们向南走，如果看见某一物种数量越来越少，就可以断定，其原因可以是别的物种受了益，也可以是这个物种受了损。向北走的情形也是这样，不过程度稍轻，因为各类的物种数量向北去都在减少，所以竞争者也减少了；因此向北走或登山时，往往就比向南走或下山时见到的植物矮小，这是由于气候的直接有害作用所致。我们到达北极区、积雪的山顶、纯粹的沙漠时，生物几乎单单是同自然环境进行生存斗争了。

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Climate plays an important part in determining the average numbers of a species, and periodical seasons of extreme cold or drought, I believe to be the most effective of all checks. I estimated that the winter of 1854-55 destroyed four-fifths of the birds in my own grounds; and this is a tremendous destruction, when we remember that ten per cent. is an extraordinarily severe mortality from epidemics with man. The action of climate seems at first sight to be quite independent of the struggle for existence; but in so far as climate chiefly acts in reducing food, it brings on the most severe struggle between the individuals, whether of the same or of distinct species, which subsist on the same kind of food. Even when climate, for instance extreme cold, acts directly, it will be the least vigorous, or those which have got least food through the advancing winter, which will suffer most. When we travel from south to north, or from a damp region to a dry, we invariably see some species gradually getting rarer and rarer, and finally disappearing; and the change of climate being conspicuous, we are tempted to attribute the whole effect to its direct action. But this is a very false view: we forget that each species, even where it most abounds, is constantly suffering enormous destruction at some period of its life, from enemies or from competitors for the same place and food; and if these enemies or competitors be in the least degree favoured by any slight change of climate, they will increase in numbers, and, as each area is already fully stocked with inhabitants, the other species will decrease. When we travel southward and see a species decreasing in numbers, we may feel sure that the cause lies quite as much in other species being favoured, as in this one being hurt. So it is when we travel northward, but in a somewhat lesser degree, for the number of species of all kinds, and therefore of competitors, decreases northwards; hence in going northward, or in ascending a mountain, we far oftener meet with stunted forms, due to the directly injurious action of climate, than we do in proceeding southwards or in descending a mountain. When we reach the Arctic regions, or snow-capped summits, or absolute deserts, the struggle for life is almost exclusively with the elements.

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花园里巨大数量的植物完全能够忍受我们的气候，但是永远不能归化，因为无法和土著植物进行斗争，也不能抵抗土著动物的侵害。显而易见，气候主要是间接起作用，有利于其他物种。

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That climate acts in main part indirectly by favouring other species, we may clearly see in the prodigious number of plants in our gardens which can perfectly well endure our climate, but which never become naturalised, for they cannot compete with our native plants, nor resist destruction by our native animals.

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如果一个物种由于高度适宜的环境条件在一个小地域内过分增殖了，常常会引起传染病的发生，至少我们的猎物一般是如此。这里的限制性抑制因素同生存斗争不相干。但是，甚至有些所谓传染病似乎是由寄生虫所致，由于某原因，部分地可能是由于动物拥挤易于传播，寄生虫不对称地受益，这里就发生了某种寄生物和寄主间的斗争。

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When a species, owing to highly favourable circumstances, increases inordinately in numbers in a small tract, epidemics—at least, this seems generally to occur with our game animals—often ensue: and here we have a limiting check independent of the struggle for life. But even some of these so-called epidemics appear to be due to parasitic worms, which have from some cause, possibly in part through facility of diffusion amongst the crowded animals, been disproportionably favoured: and here comes in a sort of struggle between the parasite and its prey.

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另一方面，在许多情形下，面对敌害，同种个体绝对需要大数量才能保存。例如，我们能轻易地在田间种植大量的五谷和油菜籽等等，因为种子和以此为食的鸟类数量相比，大为过剩，鸟在这一季里虽然食物异常丰富，却不能按照种子供给的比例增殖，其数量在冬季受抑制。人们一试便知，要想从花园里的少量小麦这类植物获得种子是多么麻烦；我就曾颗粒无收。同种的大群个体对于自身保存是必要的，这一观点，我相信可以解释自然界某些奇特的事实，例如极稀少的植物有时会在所生存的少数地方长得极其繁盛；某些丛生性植物，甚至在分布范围的边缘还能丛生，这就是说，个体是繁盛的。在这种情形下，可以相信，只有在许多个体能够共存的有利生活条件下，一种植物才能生存，这样才能抱团互助，免于全部覆灭。我还要补充一句，频繁杂交的优良效果，近亲交配的不良效果，也许在这些个案中起了作用；不过这一问题太复杂，这里不预备详述。

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On the other hand, in many cases, a large stock of individuals of the same species, relatively to the numbers of its enemies, is absolutely necessary for its preservation. Thus we can easily raise plenty of corn and rape-seed, etc., in our fields, because the seeds are in great excess compared with the number of birds which feed on them; nor can the birds, though having a superabundance of food at this one season, increase in number proportionally to the supply of seed, as their numbers are checked during winter: but any one who has tried, knows how troublesome it is to get seed from a few wheat or other such plants in a garden; I have in this case lost every single seed. This view of the necessity of a large stock of the same species for its preservation, explains, I believe, some singular facts in nature, such as that of very rare plants being sometimes extremely abundant in the few spots where they do occur; and that of some social plants being social, that is, abounding in individuals, even on the extreme confines of their range. For in such cases, we may believe, that a plant could exist only where the conditions of its life were so favourable that many could exist together, and thus save each other from utter destruction. I should add that the good effects of frequent intercrossing, and the ill effects of close interbreeding, probably come into play in some of these cases; but on this intricate subject I will not here enlarge.

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记载下来的很多个案表明，在同一地方势必进行斗争的生物之间的抑制因素和相互关系，是何等的复杂和出人意料。我只准备举一个例子，虽然简单，但我感兴趣。我亲戚在斯塔福德郡（Staffordshire）有一庄园，我在那里可以进行大量的调查。那里有一大片极度荒芜的荒地，从来没有耕种过；但有数百英亩性质完全一致的土地，曾在二十五年前圈了起来，种上了欧洲赤松（Scotch fir）。荒地种植部分的土著植物群落发生了极显著的变化，远非两片不同的土壤上可以见到的一般变化程度可比：不但荒地植物的比例数完全改变了，且有十二个植物种（不算禾本草类及苔草类）在种植园内繁生，而它们根本不见于荒地。对于昆虫的影响想必更大些，有六种不见于荒地的食虫鸟，在种植园内很普遍；而经常光顾荒地的却是两三种食虫鸟。这里我们看到，只是引进一种树便会发生多么大的影响，当时除了把土地圈起来防止牛踏进去之外，什么也没有做。但是，圈地这种要素的重要性，我曾在萨里郡（Surrey）的费勒姆（Farnham）邻近地方清楚地看到了。那里有广袤的荒地，远处小山顶上生长着几片老龄欧洲赤松。最近十年内，大块地方已圈地了，于是自然播种的赤松树层出不穷，密密麻麻挤着，无法全部存活。当我确定这些幼树并非人工播种或移植，对于它们的数量之多大感惊异，于是去了数处观测点，观察了未圈地的数百英亩荒地，除了旧时种植的几丛外，简直看不到一株欧洲赤松。但在荒地灌木的茎干之间细察时，我发现了许多幼苗和小树不时被牛吃掉了尖头。离一片老树百把码地方，一平方码的地上，共计有三十二株小树；其中一株，有二十六圈年轮，看来多年来曾试图把树顶伸出荒地灌木的树干之上，但没有成功。难怪一经圈地，便有生气勃勃的幼龄松树密布在土地上面了。可是这片荒地曾经极端荒芜而且辽阔，没有人会想象到牛竟能这样细密地来觅食，而且颇有斩获。

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Many cases are on record showing how complex and unexpected are the checks and relations between organic beings, which have to struggle together in the same country. I will give only a single instance, which, though a simple one, has interested me. In Staffordshire, on the estate of a relation where I had ample means of investigation, there was a large and extremely barren heath, which had never been touched by the hand of man; but several hundred acres of exactly the same nature had been enclosed twenty-five years previously and planted with Scotch fir. The change in the native vegetation of the planted part of the heath was most remarkable, more than is generally seen in passing from one quite different soil to another: not only the proportional numbers of the heath-plants were wholly changed, but twelve species of plants (not counting grasses and carices) flourished in the plantations, which could not be found on the heath. The effect on the insects must have been still greater, for six insectivorous birds were very common in the plantations, which were not to be seen on the heath; and the heath was frequented by two or three distinct insectivorous birds. Here we see how potent has been the effect of the introduction of a single tree, nothing whatever else having been done, with the exception that the land had been enclosed, so that cattle could not enter. But how important an element enclosure is, I plainly saw near Farnham, in Surrey. Here there are extensive heaths, with a few clumps of old Scotch firs on the distant hill-tops: within the last ten years large spaces have been enclosed, and self-sown firs are now springing up in multitudes, so close together that all cannot live. When I ascertained that these young trees had not been sown or planted, I was so much surprised at their numbers that I went to several points of view, whence I could examine hundreds of acres of the unenclosed heath, and literally I could not see a single Scotch fir, except the old planted clumps. But on looking closely between the stems of the heath, I found a multitude of seedlings and little trees, which had been perpetually browsed down by the cattle. In one square yard, at a point some hundred yards distant from one of the old clumps, I counted thirty-two little trees; and one of them, judging from the rings of growth, had during twenty-six years tried to raise its head above the stems of the heath, and had failed. No wonder that, as soon as the land was enclosed, it became thickly clothed with vigorously growing young firs. Yet the heath was so extremely barren and so extensive that no one would ever have imagined that cattle would have so closely and effectually searched it for food.

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由此可见，牛绝对决定着欧洲赤松的生存；但在若干地区，昆虫决定着牛的生存。大概巴拉圭在这方面有最奇异的事例；那里从来没有牛马或狗变成野生，但南来北往都有这些动物在野生状态下成群行动；亚莎拉（Azara）和伦格（Rengger）阐明，这是由于巴拉圭的某种蝇过多所致，这种蝇就在初生幼畜的脐中产卵。此蝇虽多，但其增殖想必常遇到某种抑制，大概是鸟类吧。因此，如果巴拉圭某种食虫鸟（其数量大概受老鹰或猛兽调节）增多了，蝇就要减少——于是牛马便可能成为野生的了，而这一定会使植物群落大为改变（我确在南美洲一些地方看到过这种现象）；同时这又会大大地影响昆虫；从而又会影响食虫鸟，恰如我们在斯塔福德郡所见，如此循环往复，复杂关系不断扩大。这个系列从食虫鸟始，又以食虫鸟终。倒不是自然界里的各种关系都可以这样简单。战斗之中套着战斗，必定反复发生，成败无常；尽管区区琐事往往能使一种生物战胜另一种生物，然而从长远看，各种势力是微妙平衡的，自然界可以长期保持划一的面貌。然而我们是多么无知，又是多么自说自话，一听到一种生物的灭绝就大惊小怪；又不知道其原因，就提出毁灭世界的灾变说，或者创造出一些法则来规定生物类型的寿命！

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Here we see that cattle absolutely determine the existence of the Scotch fir; but in several parts of the world insects determine the existence of cattle. Perhaps Paraguay offers the most curious instance of this; for here neither cattle nor horses nor dogs have ever run wild, though they swarm southward and northward in a feral state; and Azara and Rengger have shown that this is caused by the greater number in Paraguay of a certain fly, which lays its eggs in the navels of these animals when first born. The increase of these flies, numerous as they are, must be habitually checked by some means, probably by birds. Hence, if certain insectivorous birds (whose numbers are probably regulated by hawks or beasts of prey) were to increase in Paraguay, the flies would decrease—then cattle and horses would become feral, and this would certainly greatly alter (as indeed I have observed in parts of South America) the vegetation: this again would largely affect the insects; and this, as we just have seen in Staffordshire, the insectivorous birds, and so onwards in ever-increasing circles of complexity. We began this series by insectivorous birds, and we have ended with them. Not that in nature the relations can ever be as simple as this. Battle within battle must ever be recurring with varying success; and yet in the long-run the forces are so nicely balanced, that the face of nature remains uniform for long periods of time, though assuredly the merest trifle would often give the victory to one organic being over another. Nevertheless so profound is our ignorance, and so high our presumption, that we marvel when we hear of the extinction of an organic being; and as we do not see the cause, we invoke cataclysms to desolate the world, or invent laws on the duration of the forms of life!

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我想再举一个事例，说明自然界等级中相距甚远的动植物如何被复杂的关系网联结在一起。以后还有机会阐明，英格兰这个地区的外来植物亮毛半边莲（Lobelia fulgens）从来没有昆虫光顾，结果由于它的特殊构造，从不结籽。许多兰科植物都绝对需要蛾子的光顾，带走花粉块，从而使其受精。我还有理由相信，大黄蜂是三色堇（Viola tricolor）受精所不可缺少的，因为别的蜂类都不来光顾这种花。我从试验里发现，蜂类的光顾对于三叶草（clover）受精，哪怕不是不可或缺，也至少是高度有益。而只有大黄蜂才光顾红三叶草（苜蓿Trifolium pratense），因为别的蜂类都不能接触到它的花蜜。因此，我不怀疑，如果英格兰的整个大黄蜂属都灭绝了或变得稀少，三色堇和红三叶草也会变得稀少，或全部消失。任何地方的大黄蜂数量大都是由鼠的多少来决定的，田鼠毁灭蜂房蜂群。纽曼（H. Newman）先生长期研究过大黄蜂的习性，认为“全英格兰三分之二以上的大黄蜂都是这样消灭的”。众所周知，鼠的数量大多取决于猫的数量；纽曼先生说：“在村庄和小镇的附近，我看见大黄蜂窝比别的地方多，我把这一点归因于有大量的猫在捕鼠的缘故。”因此可以相信，一处地方有大量的猫科动物，先干预鼠，再干预蜂，就可以决定该地区内某些花的多少！

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I am tempted to give one more instance showing how plants and animals, most remote in the scale of nature, are bound together by a web of complex relations. I shall hereafter have occasion to show that the exotic Lobelia fulgens, in this part of England, is never visited by insects, and consequently, from its peculiar structure, never can set a seed. Many of our orchidaceous plants absolutely require the visits of moths to remove their pollen-masses and thus to fertilise them. I have, also, reason to believe that humble-bees are indispensable to the fertilisation of the heartsease (Viola tricolor), for other bees do not visit this flower. From experiments which I have tried, I have found that the visits of bees, if not indispensable, are at least highly beneficial to the fertilisation of our clovers; but humble-bees alone visit the common red clover (Trifolium pratense), as other bees cannot reach the nectar. Hence I have very little doubt, that if the whole genus of humble-bees became extinct or very rare in England, the heartsease and red clover would become very rare, or wholly disappear. The number of humble-bees in any district depends in a great degree on the number of field-mice, which destroy their combs and nests; and Mr. H. Newman, who has long attended to the habits of humble-bees, believes that “more than two-thirds of them are thus destroyed all over England.” Now the number of mice is largely dependent, as every one knows, on the number of cats; and Mr. Newman says, “Near villages and small towns I have found the nests of humble-bees more numerous than elsewhere, which I attribute to the number of cats that destroy the mice.” Hence it is quite credible that the presence of a feline animal in large numbers in a district might determine, through the intervention first of mice and then of bees, the frequency of certain flowers in that district!

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针对每一个物种，在不同的生命时期、不同的季节和年份，有多种不同的抑制因素会出现，对其发生作用；其中某一种或者某少数几种抑制作用一般最有力量，但在决定物种的平均数，乃至它的生存上，则需要共同发挥作用。有时候可以阐明，同一物种在不同地区所受到的抑制作用大相径庭。当我们看到纠缠在岸边的植物和灌木时，易于把它们的比例数和种类归因于所谓的偶然机会。但这是大错特错的！谁都听说过，美洲森林砍伐以后，便有很不同的植物群落生长起来；但已经有人谈到，美国南方的印第安古冢上现在生长的树木同周围的处女林相似，呈现了同样美丽的多样性和同样比例的各类植物。千百年来，在每年各自成千上万散播种子的若干树类之间，想必进行了十分激烈的斗争；昆虫和昆虫之间——昆虫、蜗牛等动物与猛禽、猛兽之间——进行了何等战争啊，它们都努力增殖，彼此相食，或者吃树、吃树的种子和幼苗，或者吃最初密布于地面而抑制这些树木生长的其他植物！将一把羽毛抛出，都必须依照一定的法则落到地面上；但是这个问题比起无数动植物之间的关系，就显得非常简单了，动植物的作用和反作用在千百年里决定了现今生长在印第安废墟上各类树木的比例数和树木的种类！

21
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In the case of every species, many different checks, acting at different periods of life, and during different seasons or years, probably come into play; some one check or some few being generally the most potent, but all concurring in determining the average number or even the existence of the species. In some cases it can be shown that widely-different checks act on the same species in different districts. When we look at the plants and bushes clothing an entangled bank, we are tempted to attribute their proportional numbers and kinds to what we call chance. But how false a view is this! Every one has heard that when an American forest is cut down, a very different vegetation springs up; but it has been observed that the trees now growing on the ancient Indian mounds, in the Southern United States, display the same beautiful diversity and proportion of kinds as in the surrounding virgin forests. What a struggle between the several kinds of trees must here have gone on during long centuries, each annually scattering its seeds by the thousand; what war between insect and insect—between insects, snails, and other animals with birds and beasts of prey—all striving to increase, and all feeding on each other or on the trees or their seeds and seedlings, or on the other plants which first clothed the ground and thus checked the growth of the trees! Throw up a handful of feathers, and all must fall to the ground according to definite laws; but how simple is this problem compared to the action and reaction of the innumerable plants and animals which have determined, in the course of centuries, the proportional numbers and kinds of trees now growing on the old Indian ruins!

22
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生物彼此的依存关系，有如寄生物之于寄主，一般是在性状级别远的生物之间发生的。严格意义上，彼此进行着生存斗争的生物往往如此，例如飞蝗类和食草兽。不过同种个体之间的斗争几乎都是你死我活的，因为住同一区域，需要同样的食物，还遭遇同样的危险。同种的变种之间的斗争一般差不多是同等剧烈的，而且我们有时看到争夺很快就见分晓。例如几个小麦变种混播，然后把混杂的种子再播种，那些最适于土壤气候的，或者天生最能育的变种，便会打败别的变种，结籽更多，几年之后就会将其淘汰。哪怕极度相近的变种，如颜色不同的香豌豆，混合种植时，必须每年分别采收种子，播种时再照适当的比例混合，否则弱种类的数量会不断减少而终于消灭。绵羊的变种也是这样：有人断言，某些山地绵羊变种能使另外一些变种饿死，所以不能混养。不同变种的医用蛭混养，结果也这样。让任何一种家养植物或家畜的一些变种，像在自然状况下那样相互进行斗争，假如不每年选种或拣选幼畜，那么甚至可以怀疑这些变种有没有一模一样的体力、习性和体质，足以让一个混合群的原始比例维持六代之久。

22
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The dependency of one organic being on another, as of a parasite on its prey, lies generally between beings remote in the scale of nature. This is often the case with those which may strictly be said to struggle with each other for existence, as in the case of locusts and grass-feeding quadrupeds. But the struggle almost invariably will be most severe between the individuals of the same species, for they frequent the same districts, require the same food, and are exposed to the same dangers. In the case of varieties of the same species, the struggle will generally be almost equally severe, and we sometimes see the contest soon decided: for instance, if several varieties of wheat be sown together, and the mixed seed be resown, some of the varieties which best suit the soil or climate, or are naturally the most fertile, will beat the others and so yield more seed, and will consequently in a few years quite supplant the other varieties. To keep up a mixed stock of even such extremely close varieties as the variously coloured sweet-peas, they must be each year harvested separately, and the seed then mixed in due proportion, otherwise the weaker kinds will steadily decrease in numbers and disappear. So again with the varieties of sheep: it has been asserted that certain mountain-varieties will starve out other mountain-varieties, so that they cannot be kept together. The same result has followed from keeping together different varieties of the medicinal leech. It may even be doubted whether the varieties of any one of our domestic plants or animals have so exactly the same strength, habits, and constitution, that the original proportions of a mixed stock could be kept up for half a dozen generations, if they were allowed to struggle together, like beings in a state of nature, and if the seed or young were not annually sorted.

23
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由于同属的物种通常在习性和体质方面是相似的，并且在构造方面总是相似（虽然不是绝对如此），所以之间如发生竞争，斗争一般要比异属的物种之间更剧烈。近来有一种燕子在美国局部地区拓展了，致使另一种燕子减量，可见这一点不谬。近来苏格兰一些地方槲鸫（missel-thrush）增量，导致歌鸫（song-thrush）的减量。我们不是每每听说，在千差万别的气候下一个鼠种代替了另一鼠种！在俄罗斯，小型的亚洲种蟑螂（Asiatic cockroach）入境之后，赶着大型蟑螂到处跑。一种田芥菜（charlock）将淘汰另一种，如此种种，不一而足。我们能够隐约看到，大自然系统中填补近乎相同地位的近似类型之间的竞争为什么最为剧烈；但我们大概怎么也说不确切，在伟大的生存斗争中一个物种为什么战胜了另一个物种。

23
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As species of the same genus have usually, though by no means invariably, some similarity in habits and constitution, and always in structure, the struggle will generally be more severe between species of the same genus, when they come into competition with each other, than between species of distinct genera. We see this in the recent extension over parts of the United States of one species of swallow having caused the decrease of another species. The recent increase of the missel-thrush in parts of Scotland has caused the decrease of the song-thrush. How frequently we hear of one species of rat taking the place of another species under the most different climates! In Russia the small Asiatic cockroach has everywhere driven before it its great congener. One species of charlock will supplant another, and so in other cases. We can dimly see why the competition should be most severe between allied forms, which fill nearly the same place in the economy of nature; but probably in no one case could we precisely say why one species has been victorious over another in the great battle of life.

24
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从上述可以演绎出高度重要的结论，即每一种生物的构造，以最基本然而往往是隐蔽的方式和一切其他生物的构造相关联，竞争食物或住所，要么被迫躲避它们，要么捕杀它们。在虎牙虎爪的构造上这一点很明显，攀附在虎毛上的寄生虫的腿和爪的构造也这样。但是蒲公英美丽的羽毛种子和水生甲虫扁平而生有排毛的腿，乍看似乎仅仅和空气和水有关系，但羽毛种子的优点，无疑在于和密布他种植物的地面最密切相关；这样，种子才能广泛散布，落在空地上。水生甲虫的腿的构造，非常适于潜水，以便和其他水栖昆虫竞争，捕食食物，并逃避被捕食。

24
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A corollary of the highest importance may be deduced from the foregoing remarks, namely, that the structure of every organic being is related, in the most essential yet often hidden manner, to that of all other organic beings, with which it comes into competition for food or residence, or from which it has to escape, or on which it preys. This is obvious in the structure of the teeth and talons of the tiger; and in that of the legs and claws of the parasite which clings to the hair on the tiger’s body. But in the beautifully plumed seed of the dandelion, and in the flattened and fringed legs of the water-beetle, the relation seems at first confined to the elements of air and water. Yet the advantage of plumed seeds no doubt stands in the closest relation to the land being already thickly clothed by other plants; so that the seeds may be widely distributed and fall on unoccupied ground. In the water-beetle, the structure of its legs, so well adapted for diving, allows it to compete with other aquatic insects, to hunt for its own prey, and to escape serving as prey to other animals.

25
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许多植物种子里贮藏养料，乍看似乎和其他植物没有任何关系。但是这样的种子（例如豌豆和蚕豆）播种在大草中间时，萌发的幼小植株就能茁壮生长，由此可以推知，种子中养料的主要用途是有利于幼苗生长，以便和四周繁茂的其他植物作斗争。

25
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The store of nutriment laid up within the seeds of many plants seems at first sight to have no sort of relation to other plants. But from the strong growth of young plants produced from such seeds (as peas and beans), when sown in the midst of long grass, I suspect that the chief use of the nutriment in the seed is to favour the growth of the young seedling, whilst struggling with other plants growing vigorously all around.

26
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看一看生长在分布范围中央的植物吧，为什么其数量没有翻一番、翻两番呢？我们知道它对于稍热或稍冷，稍潮湿或稍干燥的环境都能完全抵御，因为它能分布到稍热稍冷、稍湿稍干的其他地区。在此可以清楚看出，如果我们指望这种植物有能力增殖，就必须使它对竞争者、对于吃它的动物占些优势。在它的地理分布范围边缘，如果体质针对气候而发生变化，这显然有利于该植物；但有理由相信，只有少数的动植物能分布到仅仅严酷的气候就可加以消灭的远方。除非到达生活范围的极限，如北极地方或荒漠的边缘，竞争是不会停止的。有些地面可能极冷、极干，然而仍有少数几个物种或同种的个体之间为着争取最暖湿的地点而进行斗争。

26
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Look at a plant in the midst of its range, why does it not double or quadruple its numbers? We know that it can perfectly well withstand a little more heat or cold, dampness or dryness, for elsewhere it ranges into slightly hotter or colder, damper or drier districts. In this case we can clearly see that if we wished in imagination to give the plant the power of increasing in number, we should have to give it some advantage over its competitors, or over the animals which preyed on it. On the confines of its geographical range, a change of constitution with respect to climate would clearly be an advantage to our plant; but we have reason to believe that only a few plants or animals range so far, that they are destroyed by the rigour of the climate alone. Not until we reach the extreme confines of life, in the arctic regions or on the borders of an utter desert, will competition cease. The land may be extremely cold or dry, yet there will be competition between some few species, or between the individuals of the same species, for the warmest or dampest spots.

27
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由此可见，当一种动植物放置在新的地方而处于新的竞争者之中时，虽然气候可能和原产地一模一样，但生活条件一般已发生了质变。如果要它在新地方增加平均数，就得放弃在其原产地的做法，而使用不同的方法来改变它；必须使它对一批不同的竞争者和敌害占些优势。

27
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Hence, also, we can see that when a plant or animal is placed in a new country amongst new competitors, though the climate may be exactly the same as in its former home, yet the conditions of its life will generally be changed in an essential manner. If we wished to increase its average numbers in its new home, we should have to modify it in a different way to what we should have done in its native country; for we should have to give it some advantage over a different set of competitors or enemies.

28
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因此，我们不妨去设想使任何类型对其他类型占有优势。也许事到临头，我们根本不知道应该如何下手才能如愿以偿。这使我们确信，我们对于一切生物之间的相互关系实在无知；此种信念似乎难以获得，所以是必要的。我们所能做到的，就是牢牢记住，每一种生物都努力按照几何级数增殖；每一种都在生命的某一时期，一年中的某一季节，每一世代或隔代，必须进行生存斗争，并且遭受大量毁灭。想到这种斗争，我们可以安慰自己，坚信自然界的战争不是无休无止的，恐惧是感觉不到的，死亡一般是瞬间发生的，而强壮的、健康的和幸运的个体则生存并繁殖下去。

28
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It is good thus to try in our imagination to give any form some advantage over another. Probably in no single instance should we know what to do, so as to succeed. It will convince us of our ignorance on the mutual relations of all organic beings; a conviction as necessary, as it seems to be difficult to acquire. All that we can do, is to keep steadily in mind that each organic being is striving to increase at a geometrical ratio; that each at some period of its life, during some season of the year, during each generation or at intervals, has to struggle for life, and to suffer great destruction. When we reflect on this struggle, we may console ourselves with the full belief, that the war of nature is not incessant, that no fear is felt, that death is generally prompt, and that the vigorous, the healthy, and the happy survive and multiply.

序号 英文/音标 中文解释 更多操作

geometric

[ˌdʒiːə’metrɪk]

adj.几何学的;几何学图形的

genus

[’dʒiːnəs]

n.【生物学】属;类;种;型

exquisite

[ɪk’skwɪzɪt]

adj.精挑细选的;精致的;细腻的;强烈的

adaptation

[ˌædæp’teɪʃn]

n.改编;改编成的作品;适应;【心】(感官)适应，适应性变化

parasite

[’pærəsaɪt]

n.寄生虫;寄生生物;食客

dive

[daɪv]

n.潜水;跳水

plume

[pluːm]

n.羽毛;羽饰;羽状物

waft

[wɒft]

v.飘浮;飘荡

incipient

[ɪn’sɪpiənt]

adj.起初的;初期的

infinite

[’ɪnfɪnət]

adj.无穷的;无限的

preservation

[ˌprezə’veɪʃn]

n.保存

offspring

[’ɒfsprɪŋ]

n.后代;子孙;产物

periodically

[ˌpɪəri’ɒdɪkli]

adv.周期性地;定期地

incessant

[ɪn’sesnt]

adj.不断的;无尽的

feeble

[’fiːbl]

adj.虚弱的;无力的

Herbert

[hə:bət]

n.赫伯特(姓氏;男子名)

thorough

[’θʌrə]

adj.彻底的;完全的;详尽的;细致深入的

dim

[dɪm]

adj.暗淡的;模糊的;笨的

nestling

[’nestlɪŋ]

n.尚未离巢的小鸟;婴孩

prey

[preɪ]

n.牺牲者;被掠食者，猎物

recur

[rɪ’kɜː(r)]

vi.重现;再发生

dependence

[dɪ’pendəns]

n.依赖;信赖;上瘾

drought

[draʊt]

n.干旱

moisture

[’mɔɪstʃə(r)]

n.水分;潮气;湿度

seedling

[’siːdlɪŋ]

n.幼苗

disseminate

[dɪ’semɪneɪt]

vt.散播;公开;宣传

inordinate

[ɪn’ɔːdɪnət]

adj.过度的;非常的;无法无天的

manifold

[’mænɪfəʊld]

n.复印本

breeder

[’briːdə(r)]

n.饲养动物的人;培育植物的人;【核】增殖(反应)堆

astonishingly

[ə’stɒnɪʃɪŋli]

adv.惊人地;异常地

authenticate

[ɔː’θentɪkeɪt]

v.证明...为真;验证

clothe

[kləʊð]

vt.穿上;赋予

Cape

[keɪp]

n.岬;海角

diffusion

[dɪ’fjuːʒn]

n.扩散;散布

familiarity

[fəˌmɪli’ærəti]

n.亲密;熟悉;精通;不拘礼节

slaughter

[’slɔːtə(r)]

n.残杀;屠杀;大量杀戮

fluctuate

[’flʌktʃueɪt]

vi.波动;动摇;起伏

extinct

[ɪk’stɪŋkt]

adj.灭绝的;熄灭的;消亡的

indirect

[ˌɪndə’rekt]

adj.间接的;迂回的

utmost

[’ʌtməʊst]

adj.极度的;最大限度的

recurrent

[rɪ’kʌrənt]

adj.再发生的

instantaneous

[ˌɪnstən’teɪniəs]

adj.瞬间的;即刻的

wedge

[wedʒ]

n.楔子;楔形物

inwards

[’ɪnwədz]

adv.向内地.

swarm

[swɔːm]

n.群;蜂群

mankind

[mæn’kaɪnd]

n.人类;男人

ably

[’eɪbli]

adv.能干地;巧妙地

invariably

[ɪn’veəriəbli]

adv.不变地;总是;一贯地

germinate

[’dʒɜːmɪneɪt]

v.发芽;开始生长

grind

[ɡraɪnd]

v.磨;压迫;碾碎;磨得吱吱响;逐渐停顿

chiefly

[’tʃiːfli]

adv.主要地

slug

[slʌɡ]

vi. 偷懒;

turf

[tɜːf]

n.草皮;泥炭;赛马场;赛马

mow

[məʊ]

v.割(草、麦等);刈;扫射;扮鬼脸

browse

[braʊz]

v.浏览;随意观看;吃草

quadruped

[’kwɒdruped]

n.四足动物

gradual

[’ɡrædʒuəl]

adj.逐渐的;逐步的;平缓的

perish

[’perɪʃ]

vi.毁灭;消失;腐烂

partridge

[’pɑːtrɪdʒ]

n.鹧鸪

probability

[ˌprɒbə’bɪləti]

n.可能性

estimative

[’estɪmət]

n.估价;估计

tremendous

[trə’mendəs]

adj.巨大的;惊人的

cent

[sent]

n.分

conspicuous

[kən’spɪkjuəs]

adj.显著的;显眼的;显而易见的

tempting

[’temptɪŋ]

adj.诱惑人的,

abound

[ə’baʊnd]

v.富于;充满

lesser

[’lesə(r)]

adj.较少的;较小的;次要的

stunt

[stʌnt]

n.特技;阻碍成长

Arctic

[’ɑːktɪk]

adj.北极的;极寒的

tract

[trækt]

n.大片土地;器官系统

excess

[ɪk’ses]

n.超过;过量;过剩

proportional

[prə’pɔːʃənl]

adj.成比例的;相称的

singular

[’sɪŋɡjələ(r)]

a. 非凡的；卓越的;

utter

[’ʌtə(r)]

adj.完全的;全然的;绝对的

intercross

[ˌɪntɜː’krɒs]

vt.使相互交叉

interbreed

[ˌɪntə’briːd]

v.使异种交配;使混种;使杂种繁殖

enlarge

[ɪn’lɑːdʒ]

v.扩大;增大;详述

ample

[’æmpl]

adj.丰富的;宽敞的;充足的

barren

[’bærən]

adj.贫瘠的;无效的;不育的

enclose

[ɪn’kləʊz]

vt.圈起;围住;附上;封入

Scotch

[skɒtʃ]

n.伤口;刻痕

vegetation

[ˌvedʒə’teɪʃn]

n.植物;草木

wholly

[’həʊlli]

adv.完全地;全部地;一概

enclosure

[ɪn’kləʊʒə(r)]

n.附件;围墙;围绕

clump

[klʌmp]

n.丛;块;沉重的声音

ascertain

[ˌæsə’teɪn]

vt.确定;查明;探知

sow

[saʊ]

v.播种;散布

perpetual

[pə’petʃuəl]

adj.永久的;永恒的;一再往复的

navel

[’neɪvl]

n.肚脐;中心

habitual

[hə’bɪtʃuəl]

adj.惯常的;习惯的

hawk

[hɔːk]

vt. 叫卖；吆喝;

ignorance

[’ɪɡnərəns]

n.无知;愚昧

invoke

[ɪn’vəʊk]

vt.援引;引起;求助;请求

cataclysm

[’kætəklɪzəm]

n.大洪水;地震;(社会政治的)大变动

duration

[dju’reɪʃn]

n.持续时间

moth

[mɒθ]

n.蠹;蛾

clover

[’kləʊvə(r)]

n.三叶草;苜蓿

entangle

[ɪn’tæŋɡl]

vt. 使 ... 纠缠; 使 ... 复杂; 卷入; 使 ... 混乱

mound

[maʊnd]

n.土墩;小丘;一堆

dependency

[dɪ’pendənsi]

n.依赖;属国;从属物

locust

[’ləʊkəst]

n.蝗虫;洋槐;刺槐

fertile

[’fɜːtaɪl]

adj.肥沃的;富饶的;能繁殖的;多产的;(创造力)丰富的

harvestable

[’hɑːvɪstəbl]

n.收成;收获;收割;成果;后果

medicinal

[mə’dɪsɪnl]

adj.药物的;有药味的;治疗的;医学的

talon

[’tælən]

n.爪;手;爪状物;发剩的牌

claw

[klɔː]

n.爪;钳;螯;爪状物

aquatic

[ə’kwætɪk]

adj.水生的;水中的;水上的

quadruple

[kwɒ’druːpl]

adj.四倍的;四部分的;【音】四节拍的

dampness

[’dæmpnəs]

n.潮湿;湿度;含水量

dryness

[draɪnəs]

n.干燥;冷淡

damper

[’dæmpə(r)]

n.风阀;减音器;阻尼器;抑制

drier

[’draɪə]

n.吹风机;干燥机;干燥工;干燥剂.

arctic

[’ɑːktɪk]

adj.北极的;极寒的

console

[kən’səʊl]

vt.安慰;慰藉

felted

[’feltɪd]

v. 把 ... 制成毡(使 ... 粘结)

multiply

[’mʌltɪplaɪ]

vt.乘;增加

incessant

[ɪn’sesnt]

adj.不断的;无尽的

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