登陆注册
5618700000008

第8章

I know nothing that more appropriately expresses this, than the phrase, "the struggle for existence"; because it brings before your minds, in a vivid sort of way, some of the simplest possible circumstances connected with it.When a struggle is intense there must be some who are sure to be trodden down, crushed, and overpowered by others; and there will be some who just manage to get through only by the help of the slightest accident.I recollect reading an account of the famous retreat of the French troops, under Napoleon, from Moscow.Worn out, tired, and dejected, they at length came to a great river over which there was but one bridge for the passage of the vast army.Disorganised and demoralised as that army was, the struggle must certainly have been a terrible one--every one heeding only himself, and crushing through the ranks and treading down his fellows.The writer of the narrative, who was himself one of those who were fortunate enough to succeed in getting over, and not among the thousands who were left behind or forced into the river, ascribed his escape to the fact that he saw striding onward through the mass a great strong fellow,--one of the French Cuirassiers, who had on a large blue cloak--and he had enough presence of mind to catch and retain a hold of this strong man's cloak.He says, "I caught hold of his cloak, and although he swore at me and cut at and struck me by turns, and at last, when he found he could not shake me off, fell to entreating me to leave go or I should prevent him from escaping, besides not assisting myself, I still kept tight hold of him, and would not quit my grasp until he had at last dragged me through." Here you see was a case of selective saving--if we may so term it--depending for its success on the strength of the cloth of the Cuirassier's cloak.It is the same in nature; every species has its bridge of Beresina; it has to fight its way through and struggle with other species; and when well nigh overpowered, it may be that the smallest chance, something in its colour, perhaps--the minutest circumstance--will turn the scale one way or the other.

Suppose that by a variation of the black race it had produced the white man at any time--you know that the Negroes are said to believe this to have been the case, and to imagine that Cain was the first white man, and that we are his descendants--suppose that this had ever happened, and that the first residence of this human being was on the West Coast of Africa.There is no great structural difference between the white man and the Negro, and yet there is something so singularly different in the constitution of the two, that the malarias of that country, which do not hurt the black at all, cut off and destroy the white.Then you see there would have been a selective operation performed; if the white man had risen in that way, he would have been selected out and removed by means of the malaria.Now there really is a very curious case of selection of this sort among pigs, and it is a case of selection of colour too.In the woods of Florida there are a great many pigs, and it is a very curious thing that they are all black, every one of them.

Professor Wyman was there some years ago, and on noticing no pigs but these black ones, he asked some of the people how it was that they had no white pigs, and the reply was that in the woods of Florida there was a root which they called the Paint Root, and that if the white pigs were to eat any of it, it had the effect of making their hoofs crack, and they died, but if the black pigs eat any of it, it did not hurt them at all.Here was a very simple case of natural selection.Askilful breeder could not more carefully develope the black breed of pigs, and weed out all the white pigs, than the Paint Root does.

To show you how remarkably indirect may be such natural selective agencies as I have referred to, I will conclude by noticing a case mentioned by Mr.Darwin, and which is certainly one of the most curious of its kind.It is that of the Humble Bee.It has been noticed that there are a great many more humble bees in the neighbourhood of towns, than out in the open country; and the explanation of the matter is this: the humble bees build nests, in which they store their honey and deposit the larvae and eggs.The field mice are amazingly fond of the honey and larvae; therefore, wherever there are plenty of field mice, as in the country, the humble bees are kept down; but in the neighbourhood of towns, the number of cats which prowl about the fields eat up the field mice, and of course the more mice they eat up the less there are to prey upon the larvae of the bees--the cats are therefore the INDIRECTHELPERS of the bees!* Coming back a step farther we may say that the old maids are also indirect friends of the humble bees, and indirect enemies of the field mice, as they keep the cats which eat up the latter! This is an illustration somewhat beneath the dignity of the subject, perhaps, but it occurs to me in passing, and with it I will conclude this lecture.

[footnote] *The humble bees, on the other hand, are direct helpers of some plants, such as the heartsease and red clover, which are fertilized by the visits of the bees; and they are indirect helpers of the numerous insects which are more or less completely supported by the heartsease and red clover.

End

同类推荐
热门推荐
  • 飘

    描写的历史背景是1861年美国南北战期间,南方佐治亚州塔拉庄园的园主16岁的长女思嘉爱上了艾希礼,后来艾希礼要和一位叫媚兰的姑娘结婚。思嘉气极之下嫁给媚兰的哥哥查尔斯。后来查尔斯和艾希礼一起应征入伍,但查尔斯在入伍后不久就病故了,军火商端德趁机博得了思嘉的芳心。思嘉的家几乎遭到了北方军队的毁灭。南方军队战败,艾希礼回来了。俩人又重温旧梦,但艾希礼无法答应和她一起私奔。思嘉为了保护自己的庄园,千方百计博得了有钱人弗兰克的信任,并委身于他,弗兰克死后,思嘉不得已又和瑞德结婚。不久,经过太多磨难的瑞德对她已不太信任,下决心和她离婚。而思嘉深知真爱自己的人是瑞德,她决心重新找回爱她的瑞德。
  • 红颜战神0a

    红颜战神0a

    妇好,中国历史上有据可查的第一位女性军事统帅,还主持着各种祭祀活动。红妆武装她都爱。出生便经历狼叼虎衔之异象。幼年丧母,血海深仇。儿时玩伴,昔日商王。南征北战,所向披靡。千古一后,前无来者!甲骨文中,多次记载,武丁和妇好将部属们甩在后面,两人一起并肩驱策,在旷野中追逐驰骋。琴瑟和谐,羡煞后人……
  • 经典躺着读(先秦—元明卷)

    经典躺着读(先秦—元明卷)

    全书叙述分析从先秦至明代,影响中国古代文学史的重要作品,从《诗经》中男女咏歌言情到先秦老庄,唐代李白杜甫白居易,宋朝王安石与苏东坡,到《三国演义》《水浒传》《金瓶梅》等小说,以汤显祖达到中国古典戏剧高峰的《牡丹亭》作结,三十一篇文章或侧重作家或侧重作品,尽现中国古文化及文人的不同姿态,展现中国古代文学“从自发到自觉”的自我完善历程。
  • 甜宠不停,男神纵妻无度

    甜宠不停,男神纵妻无度

    推荐新文《青春蜜恋:这个校霸有点甜》。[宠文1V1]安曦玥睡了男神,男神非要负责,安曦玥:“我不答应啊,我还那么小,睡一次就要负责你是在耍流氓。”于是她逃了。逃了四年,带了个养女回来。男神非得说女儿是他们俩的,还去验了DNA。DNA结果有些诡异,孩子变成了男神的种。安曦玥被迫嫁给男神,说好为了孩子没错,可我不是你孩子的亲妈耶,还有。你对我为何那么宠?小包子:“我真是你女儿?”男神:“当然是。”小包子:“可你不是号称只爱我麻麻一人吗?我不是麻麻亲生的,你居然还跟我妈有一腿,渣男!”男神:“……你妈妈失忆了,她确实是你亲妈。”小包子:“到底谁傻?”
  • Hi,慕少的360花样蜜爱

    Hi,慕少的360花样蜜爱

    遇见是一见倾心,相遇美好,但结局是意想不到,那是的我们还不知道如何去爱,明白之后才发现你已不在……
  • 星际直播之我是大明星

    星际直播之我是大明星

    陆林重生了,重生到了一个同地球一样的水蓝星上,而且还附体到了一位明星身上。这直播是什么鬼?陆林无语了,我不想做什么主播啊!我只想当明星!这是直播,也不是直播,这只是一个明星直播到星际的故事!!!星际直播,书友交流群:483540051V群交流:580056165PS:老书《天庭阅读器》已完本,有兴趣的朋友可以去看一下。
  • 境界碾压系统

    境界碾压系统

    苍鸣意外穿越成一个混吃等死的沧澜宗少宗主,牛叉老爹因斩杀神级宗门真传弟子,被宗门仲裁会抓判无期徒刑,想要拯救父亲就得将宗门提升至神级宗门。好在本少有“境界碾压系统”一路碾压天才,将其收入宗门,何愁不成神宗。“这么天才?高你一阶我都打不过你。”“这般生猛?高你两阶我还打不过你。”“行吧!高你一个大境界总可以调教调教你吧!单纯的境界碾压,你奈我何?”
  • 妃常霸道:玩转异世

    妃常霸道:玩转异世

    倾心相遇,安暖相陪墨卿墨卿莫负卿,梓吟,这辈子我定不负你。古说:青青子衿,悠悠我心我说:青青梓吟,君故至今墨卿,遇见你是我这辈子最大的幸运。她从异世穿越,恰巧赶上史上最狗血剧情。听闻前身爹不疼娘失踪;白莲花和绿茶婊…对于穿越而来的她,这都不叫事。别人梦寐以求的东西,转手得来。直到她遇见他,千百相逢,谁是谁的劫?他是万千少女着迷对象。“陌上人如玉,公子世无双”的男神级人物。可他从未对谁上心,从未在乎过世间万千,直到遇见她,毫无波纹的人生,第一次起了波澜。“原来这世间万物,还会这么好看。只因有你罢了。”『本文男强女强,时不时撒小粉心喔?』
  • 绝色药师:帝尊,心尖宠

    绝色药师:帝尊,心尖宠

    萧团团,一代陨落的天才,本以为会被人踩在脚底肆意践踏,奈何人家有一个神仙般的伴侣,不仅不嫌弃她没有实力,更是将其宠成了人人都羡慕的样子。整天‘不思进取’也就罢了,还运气好的吓人,什么极品晶石,罕见灵兽,捡的她都没激情了。蠢作者采访:对此你有什么看法?萧团团:胡说,明明我也有宠他!
  • 追妻无门:女boss不好惹

    追妻无门:女boss不好惹

    青涩蜕变,如今她是能独当一面的女boss,爱了冷泽聿七年,也同样花了七年时间去忘记他。以为是陌路,他突然向他表白,扬言要娶她,她只当他是脑子抽风,他的殷勤她也全都无视。他帮她查她父母的死因,赶走身边情敌,解释当初拒绝她的告别,和故意对她冷漠都是无奈之举。突然爆出她父母的死居然和冷家有丝毫联系,还莫名跳出个公爵未婚夫,扬言要与她履行婚约。峰回路转,破镜还能重圆吗? PS:我又开新文了,每逢假期必书荒,新文《有你的世界遇到爱》,喜欢我的文的朋友可以来看看,这是重生类现言,对这个题材感兴趣的一定要收藏起来。