X. DISTANT RELATIONS.

Behind the old mill, whose overshot wheel, backed by a wall thickly covered with the young creeping fronds² of hart's-tongue ferns, forms such a picturesque³ foreground for the view of our little valley, the mill-stream expands into a small shallow pond, overhung at its edges by thick-set hazel-bushes and clambering honeysuckle. Of course it is only dammed back by a mud wall, with sluices⁵ for the miller's water-power; but it has a certain rustic⁶ simplicity⁷ of its own, which makes it beautiful to our eyes for all that, in spite of its utilitarian⁸ origin. At the bottom of this shallow pond you may now see a miracle daily taking place, which but for its commonness we should regard as an almost incredible marvel⁹. You may there behold¹⁰ evolution actually illustrating¹¹ the transformation¹² of life under your very eyes: you may watch a low type of gill-breathing gristly-boned fish developing into the highest form of lung-breathing terrestrial amphibian¹³. Nay¹⁴, more—you may almost discover the earliest known ancestor of the whole vertebrate kind, the first cousin of that once famous ascidian larva, passing through all the upward stages of existence which finally lead it to assume the shape of a relatively¹⁵ perfect four-legged animal. For the pond is swarming¹⁶ with fat black tadpoles¹⁷, which are just at this moment losing their tails and developing their legs, on the way to becoming fully¹⁹ formed frogs.

The tadpole¹⁸ and the ascidian larva divide between them the honour of preserving for us in all its native simplicity the primitive²⁰ aspect of the vertebrate type. Beasts, birds, reptiles²², and fishes have all descended²³ from an animal whose shape closely resembled that of these wriggling²⁴ little black creatures which dart²⁵ up and down like imps²⁶ through the clear water, and raise a cloud of mud above their heads each time that they bury themselves comfortably in the soft mud of the bottom. But while the birds and beasts, on the one hand, have gone on bettering themselves out of all knowledge, and while the ascidian, on the other hand, in his adult form has dropped back into an obscure and sedentary life—sans eyes, sans teeth, sans taste, sans everything—the tadpole alone, at least during its early days, remains²⁷ true to the ancestral traditions of the vertebrate family. When first it emerges from its egg it represents the very most rudimentary animal with a backbone²⁸ known to our scientific teachers. It has a big hammer-looking head, and a set of branching outside gills, and a short distinct body, and a long semi-transparent²⁹ tail. Its backbone is a mere³⁰ gristly channel, in which lies its spinal³¹ cord. As it grows, it resembles in every particular the ascidian larva, with which, indeed, Kowalewsky and Professor Ray Lankester have demonstrated its essential identity. But since a great many people seem wrongly to imagine that Professor Lankester's opinion on this matter is in some way at variance³² with Mr. Darwin's and Dr. Haeckel's, it may be well to consider what the degeneracy of the ascidian really means. The fact is, both larval forms—that of the frog and that of the ascidian—completely agree in the position of their brains, their gill-slits, their very rudimentary backbones³³, and their spinal cords. Moreover, we ourselves and the tadpole agree with the ascidian in a further most important point, which no invertebrate³⁴ animal shares with us; and that is that our eyes grow out of our brains, instead of being part of our skin, as in insects and cuttle-fish. This would seem à priori a most inconvenient³⁵ place for an eye—inside the brain; but then, as Professor Lankester cleverly suggests, our common original ancestor, the very earliest vertebrate of all, must have been a transparent creature, and therefore comparatively indifferent as to the part of his body in which his eye happened to be placed. In after ages, however, as vertebrates generally got to have thicker skulls³⁶ and tougher skins, the eye-bearing part of the brain had to grow outward, and so reach the light on the surface of the body: a thing which actually happens to all birds, beasts, and reptiles in the course of their embryonic³⁷ development. So that in this respect the ascidian larva is nearer to the original type than the tadpole or any other existing animal.

The ascidian, however, in mature life, has grown degraded and fallen from his high estate, owing to his bad habit of rooting himself to a rock and there settling down into a mere sedentary swallower of passing morsels—a blind, handless, footless, and degenerate³⁸ thing. In his later shape he is but a sack fixed³⁹ to a stone, and with all his limbs and higher sense-organs so completely atrophied⁴⁰ that only his earlier history allows us to recognise him as a vertebrate by descent at all. He is in fact a representative of retrogressive development. The tadpole, on the contrary, goes on swimming about freely, and keeping the use of its eyes, till at last a pair of hind¹ legs and then a pair of fore⁴ legs begin to bud out from its side, and its tail fades away, and its gills disappear, and air-breathing lungs take their place, and it boldly hops⁴¹ on shore a fully evolved tailless amphibian.

There is, however, one interesting question about these two larv? which I should much like to solve. The ascidian has only one eye inside its useless brain, while the tadpole and all other vertebrates have two from the very first. Now which of us most nearly represents the old mud-loving vertebrate ancestor in this respect? Have two original organs coalesced⁴² in the young ascidian, or has one organ split up into a couple with the rest of the class? I think the latter is the true supposition, and for this reason: In our heads, and those of all vertebrates, there is a curious cross-connection between the eyes and the brain, so that the right optic nerve goes to the left side of the brain and the left optic nerve goes to the right side. In higher animals, this 'decussation,' as anatomists call it, affects all the sense-organs except those of smell; but in fishes it only affects the eyes. Now, as the young ascidian has retained the ancestral position of his almost useless eye so steadily⁴³, it is reasonable to suppose that he has retained its other peculiarities⁴⁴ as well. May we not conclude, therefore, that the primitive vertebrate had only one brain-eye; but that afterwards, as this brain-eye grew outward to the surface, it split up into two, because of the elongated⁴⁵ and flattened⁴⁶ form of the head in swimming animals, while its two halves still kept up a memory of their former union in the cross-connection with the opposite halves of the brain? If this be so, then we might suppose that the other organs followed suit, so as to prevent confusion in the brain between the two sides of the body; while the nose, which stands in the centre of the face, was under no liability to such error, and therefore still keeps up its primitive direct arrangement.

It is worth noting, too, that these tadpoles, like all other very low vertebrates, are mud-haunters; and the most primitive among adult vertebrates are still cartilaginous mud-fish. Not much is known geologically about the predecessors⁴⁷ of frogs; the tailless amphibians⁴⁸ are late arrivals upon earth, and it may seem curious, therefore, that they should recall in so many ways the earliest ancestral type. The reason doubtless is because they are so much given to larval development. Some ancestors of theirs—prim²¹?val newts or salamanders—must have gone on for countless⁴⁹ centuries improving themselves in their adult shape from age to age, yet bringing all their young into the world from the egg, as mere mud-fish still, in much the same state as their unimproved forefathers⁵⁰ had done millions of ?ons before. Similarly, caterpillars⁵¹ are still all but exact patterns of the prim?val insect, while butterflies are totally different and far higher creatures. Thus, in spite of adult degeneracy in the ascidian and adult progress in the frog, both tadpoles preserve for us very nearly the original form of their earliest backboned ancestor. Each individual recapitulates⁵² in its own person the whole history of evolution in its race. This is a very lucky thing for biology; since without these recapitulatory⁵³ phases we could never have traced the true lines of descent in many cases. It would be a real misfortune for science if every frog had been born a typical amphibian, as some tree-toads actually are, and if every insect had emerged a fully formed adult, as some aphides very nearly do. Larv? and embryos⁵⁴ show us the original types of each race; adults show us the total amount of change produced by progressive or retrogressive development.

1 hind   

adj.后面的，后部的

参考例句：

• The animal is able to stand up on its hind limbs.这种动物能够用后肢站立。
• Don't hind her in her studies.不要在学业上扯她后腿。

2 fronds   

n.蕨类或棕榈类植物的叶子( frond的名词复数 )

参考例句：

• You can pleat palm fronds to make huts, umbrellas and baskets. 人们可以把棕榈叶折叠起来盖棚屋，制伞，编篮子。 来自百科语句
• When these breezes reached the platform the palm-fronds would whisper. 微风吹到平台时，棕榈叶片发出簌簌的低吟。 来自辞典例句

3 picturesque   

adj.美丽如画的，（语言）生动的，绘声绘色的

参考例句：

• You can see the picturesque shores beside the river.在河边你可以看到景色如画的两岸。
• That was a picturesque phrase.那是一个形象化的说法。

4 fore   

adv.在前面；adj.先前的；在前部的；n.前部

参考例句：

• Your seat is in the fore part of the aircraft.你的座位在飞机的前部。
• I have the gift of fore knowledge.我能够未卜先知。

5 sluices   

n.水闸( sluice的名词复数 )；（用水闸控制的）水；有闸人工水道；漂洗处v.冲洗( sluice的第三人称单数 )；（指水）喷涌而出；漂净；给…安装水闸

参考例句：

• Excess water will drain through sluices into the sea. 过剩的水将会通过水闸排放到海里去。 来自英语晨读30分（高二）
• The sluices had already been opened, and with every day the floods were spreading. 水闸已经打开，洪水逐日奔流。 来自辞典例句

6 rustic   

adj.乡村的，有乡村特色的；n.乡下人，乡巴佬

参考例句：

• It was nearly seven months of leisurely rustic living before Michael felt real boredom.这种悠闲的乡村生活过了差不多七个月之后,迈克尔开始感到烦闷。
• We hoped the fresh air and rustic atmosphere would help him adjust.我们希望新鲜的空气和乡村的氛围能帮他调整自己。

7 simplicity   

n.简单，简易；朴素；直率，单纯

参考例句：

• She dressed with elegant simplicity.她穿着朴素高雅。
• The beauty of this plan is its simplicity.简明扼要是这个计划的一大特点。

8 utilitarian   

adj.实用的，功利的

参考例句：

• On the utilitarian side American education has outstridden the rest of the world.在实用方面美国教育已超越世界各国。
• A good cloth coat is more utilitarian than a fur one.一件优质的布外衣要比一件毛皮外衣更有用。

9 marvel   

vi.(at)惊叹vt.感到惊异；n.令人惊异的事

参考例句：

• The robot is a marvel of modern engineering.机器人是现代工程技术的奇迹。
• The operation was a marvel of medical skill.这次手术是医术上的一个奇迹。

10 behold   

v.看，注视，看到

参考例句：

• The industry of these little ants is wonderful to behold.这些小蚂蚁辛勤劳动的样子看上去真令人惊叹。
• The sunrise at the seaside was quite a sight to behold.海滨日出真是个奇景。

11 illustrating   

给…加插图( illustrate的现在分词 )； 说明； 表明； （用示例、图画等）说明

参考例句：

• He upstaged the other speakers by illustrating his talk with slides. 他演讲中配上幻灯片，比其他演讲人更吸引听众。
• Material illustrating detailed structure of graptolites has been etched from limestone by means of hydrofluoric acid. 表明笔石详细构造的物质是利用氢氟酸从石灰岩中侵蚀出来。

12 transformation   

n.变化；改造；转变

参考例句：

• Going to college brought about a dramatic transformation in her outlook.上大学使她的观念发生了巨大的变化。
• He was struggling to make the transformation from single man to responsible husband.他正在努力使自己由单身汉变为可靠的丈夫。

13 amphibian   

n.两栖动物；水陆两用飞机和车辆

参考例句：

• The frog is an amphibian,which means it can live on land and in water.青蛙属于两栖动物，也就是说它既能生活在陆地上也能生活在水里。
• Amphibian is an important specie in ecosystem and has profound meaning in the ecotoxicology evaluation.两栖类是生态系统中的重要物种，并且对环境毒理评价有着深远意义。

14 nay   

adv.不；n.反对票，投反对票者

参考例句：

• He was grateful for and proud of his son's remarkable,nay,unique performance.他为儿子出色的，不，应该是独一无二的表演心怀感激和骄傲。
• Long essays,nay,whole books have been written on this.许多长篇大论的文章，不，应该说是整部整部的书都是关于这件事的。

15 relatively   

adv.比较...地，相对地

参考例句：

• The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
• The operation was relatively painless.手术相对来说不痛。

16 swarming   

密集( swarm的现在分词 )； 云集； 成群地移动； 蜜蜂或其他飞行昆虫成群地飞来飞去

参考例句：

• The sacks of rice were swarming with bugs. 一袋袋的米里长满了虫子。
• The beach is swarming with bathers. 海滩满是海水浴的人。

17 tadpoles   

n.蝌蚪( tadpole的名词复数 )

参考例句：

• The pond teemed with tadpoles. 池子里有很多蝌蚪。 来自《简明英汉词典》
• Both fish and tadpoles have gills. 鱼和蝌蚪都有鳃。 来自《现代汉英综合大词典》

18 tadpole   

n.[动]蝌蚪

参考例句：

• As a tadpole changes into a frog,its tail is gradually absorbed.蝌蚪变成蛙，它的尾巴就逐渐被吸收掉。
• It was a tadpole.Now it is a frog.它过去是蝌蚪，现在是一只青蛙。

19 fully   

adv.完全地，全部地，彻底地；充分地

参考例句：

• The doctor asked me to breathe in,then to breathe out fully.医生让我先吸气，然后全部呼出。
• They soon became fully integrated into the local community.他们很快就完全融入了当地人的圈子。

20 primitive   

adj.原始的；简单的；n.原(始)人，原始事物

参考例句：

• It is a primitive instinct to flee a place of danger.逃离危险的地方是一种原始本能。
• His book describes the march of the civilization of a primitive society.他的著作描述了一个原始社会的开化过程。

21 prim   

adj.拘泥形式的，一本正经的；n.循规蹈矩，整洁；adv.循规蹈矩地，整洁地

参考例句：

• She's too prim to enjoy rude jokes!她太古板，不喜欢听粗野的笑话！
• He is prim and precise in manner.他的态度一本正经而严谨

22 reptiles   

n.爬行动物，爬虫( reptile的名词复数 )

参考例句：

• Snakes and crocodiles are both reptiles. 蛇和鳄鱼都是爬行动物。 来自《简明英汉词典》
• Birds, reptiles and insects come from eggs. 鸟类、爬虫及昆虫是卵生的。 来自《现代汉英综合大词典》

23 descended   

a.为...后裔的，出身于...的

参考例句：

• A mood of melancholy descended on us. 一种悲伤的情绪袭上我们的心头。
• The path descended the hill in a series of zigzags. 小路呈连续的之字形顺着山坡蜿蜒而下。

24 wriggling   

v.扭动，蠕动，蜿蜒行进( wriggle的现在分词 )；（使身体某一部位）扭动；耍滑不做，逃避（应做的事等）；蠕蠕

参考例句：

• The baby was wriggling around on my lap. 婴儿在我大腿上扭来扭去。
• Something that looks like a gray snake is wriggling out. 有一种看来象是灰蛇的东西蠕动着出来了。 来自辞典例句

25 dart   

v.猛冲，投掷；n.飞镖，猛冲

参考例句：

• The child made a sudden dart across the road.那小孩突然冲过马路。
• Markov died after being struck by a poison dart.马尔科夫身中毒镖而亡。

26 imps   

n.（故事中的）小恶魔( imp的名词复数 )；小魔鬼；小淘气；顽童

参考例句：

• Those imps are brewing mischief. 那些小淘气们正在打坏主意。 来自辞典例句
• No marvel if the imps follow when the devil goes before. 魔鬼带头，难怪小鬼纷纷跟随。 来自互联网

27 remains   

n.剩余物，残留物；遗体，遗迹

参考例句：

• He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
• The remains of the meal were fed to the dog.残羹剩饭喂狗了。

28 backbone   

n.脊骨，脊柱，骨干；刚毅，骨气

参考例句：

• The Chinese people have backbone.中国人民有骨气。
• The backbone is an articulate structure.脊椎骨是一种关节相连的结构。

29 transparent   

adj.明显的，无疑的；透明的

参考例句：

• The water is so transparent that we can see the fishes swimming.水清澈透明，可以看到鱼儿游来游去。
• The window glass is transparent.窗玻璃是透明的。

30 mere   

adj.纯粹的；仅仅，只不过

参考例句：

• That is a mere repetition of what you said before.那不过是重复了你以前讲的话。
• It's a mere waste of time waiting any longer.再等下去纯粹是浪费时间。

31 spinal   

adj.针的，尖刺的，尖刺状突起的；adj.脊骨的，脊髓的

参考例句：

• After three days in Japan,the spinal column becomes extraordinarily flexible.在日本三天，就已经使脊椎骨变得富有弹性了。
• Your spinal column is made up of 24 movable vertebrae.你的脊柱由24个活动的脊椎骨构成。

32 variance   

n.矛盾，不同

参考例句：

• The question of woman suffrage sets them at variance. 妇女参政的问题使他们发生争执。
• It is unnatural for brothers to be at variance. 兄弟之间不睦是不近人情的。

33 backbones   

n.骨干( backbone的名词复数 )；脊骨；骨气；脊骨状物

参考例句：

• Why do hummingbirds and gorillas both have backbones? 为什么蜂鸟和大猩猩都有脊骨？ 来自辞典例句
• Simply adding bandwidth to the Internet backbones is not an answer. 只是简单的在互联网骨架上增加带宽是应付不了的。 来自互联网

34 invertebrate   

n.无脊椎动物

参考例句：

• Half of all invertebrate species live in tropical rain forests.一半的无脊椎动物物种生活在热带雨林中。
• Worms are an example of invertebrate animals.蠕虫是无脊椎动物的一个例子。

35 inconvenient   

adj.不方便的，令人感到麻烦的

参考例句：

• You have come at a very inconvenient time.你来得最不适时。
• Will it be inconvenient for him to attend that meeting?他参加那次会议会不方便吗？

36 skulls   

颅骨( skull的名词复数 )； 脑袋； 脑子； 脑瓜

参考例句：

• One of the women's skulls found exceeds in capacity that of the average man of today. 现已发现的女性颅骨中，其中有一个的脑容量超过了今天的普通男子。
• We could make a whole plain white with skulls in the moonlight! 我们便能令月光下的平原变白，遍布白色的骷髅！

37 embryonic   

adj.胚胎的

参考例句：

• It is still in an embryonic stage.它还处于萌芽阶段。
• The plan,as yet,only exists in embryonic form.这个计划迄今为止还只是在酝酿之中。

38 degenerate   

v.退步，堕落；adj.退步的，堕落的；n.堕落者

参考例句：

• He didn't let riches and luxury make him degenerate.他不因财富和奢华而自甘堕落。
• Will too much freedom make them degenerate?太多的自由会令他们堕落吗？

39 fixed   

adj.固定的，不变的，准备好的；(计算机)固定的

参考例句：

• Have you two fixed on a date for the wedding yet?你们俩选定婚期了吗？
• Once the aim is fixed,we should not change it arbitrarily.目标一旦确定，我们就不应该随意改变。

40 atrophied   

adj.萎缩的，衰退的v.（使）萎缩，（使）虚脱，（使）衰退( atrophy的过去式和过去分词 )

参考例句：

• Patients exercised their atrophied limbs in the swimming pool. 病人们在泳池里锻炼萎缩的四肢。 来自辞典例句
• Method: Using microwave tissue thermocoaqulation to make chronic tonsillitis coagulated and atrophied. 方法：采用微波热凝方法使慢性扁桃体炎组织凝固、萎缩。 来自互联网

41 hops   

跳上[下]( hop的第三人称单数 )； 单足蹦跳； 齐足（或双足）跳行； 摘葎草花

参考例句：

• The sparrow crossed the lawn in a series of hops. 那麻雀一蹦一跳地穿过草坪。
• It is brewed from malt and hops. 它用麦精和蛇麻草酿成。

42 coalesced   

v.联合，合并( coalesce的过去式和过去分词 )

参考例句：

• The puddles had coalesced into a small stream. 地面上水洼子里的水汇流成了一条小溪。
• The views of party leaders coalesced to form a coherent policy. 党的领导人的各种观点已统一为一致的政策。 来自辞典例句

43 steadily   

adv.稳定地；不变地；持续地

参考例句：

• The scope of man's use of natural resources will steadily grow.人类利用自然资源的广度将日益扩大。
• Our educational reform was steadily led onto the correct path.我们的教学改革慢慢上轨道了。

44 peculiarities   

n. 特质, 特性, 怪癖, 古怪

参考例句：

• the cultural peculiarities of the English 英国人的文化特点
• He used to mimic speech peculiarities of another. 他过去总是模仿别人讲话的特点。

45 elongated   

v.延长，加长( elongate的过去式和过去分词 )

参考例句：

• Modigliani's women have strangely elongated faces. 莫迪里阿尼画中的妇女都长着奇长无比的脸。
• A piece of rubber can be elongated by streching. 一块橡皮可以拉长。 来自《用法词典》

46 flattened   

[医]（水）平扁的，弄平的

参考例句：

• She flattened her nose and lips against the window. 她把鼻子和嘴唇紧贴着窗户。
• I flattened myself against the wall to let them pass. 我身体紧靠着墙让他们通过。

47 predecessors   

n.前任( predecessor的名词复数 )；前辈；（被取代的）原有事物；前身

参考例句：

• The new government set about dismantling their predecessors' legislation. 新政府正着手废除其前任所制定的法律。 来自《简明英汉词典》
• Will new plan be any more acceptable than its predecessors? 新计划比原先的计划更能令人满意吗？ 来自《简明英汉词典》

48 amphibians   

两栖动物( amphibian的名词复数 )； 水陆两用车； 水旱两生植物； 水陆两用飞行器

参考例句：

• The skin of amphibians is permeable to water. 两栖动物的皮肤是透水的。
• Two amphibians ferry them out over the sands. 两辆水陆两用车把他们渡过沙滩。

49 countless   

adj.无数的，多得不计其数的

参考例句：

• In the war countless innocent people lost their lives.在这场战争中无数无辜的人丧失了性命。
• I've told you countless times.我已经告诉你无数遍了。

50 forefathers   

n.祖先，先人；祖先，祖宗( forefather的名词复数 )；列祖列宗；前人

参考例句：

• They are the most precious cultural legacy our forefathers left. 它们是我们祖先留下来的最宝贵的文化遗产。 来自《简明英汉词典》
• All of us bristled at the lawyer's speech insulting our forefathers. 听到那个律师在讲演中污蔑我们的祖先，大家都气得怒发冲冠。 来自《简明英汉词典》

51 caterpillars   

n.毛虫( caterpillar的名词复数 )；履带

参考例句：

• Caterpillars eat the young leaves of this plant. 毛毛虫吃这种植物的嫩叶。
• Caterpillars change into butterflies or moths. 毛虫能变成蝴蝶或蛾子。 来自辞典例句

52 recapitulates   

n.总结，扼要重述( recapitulate的名词复数 )v.总结，扼要重述( recapitulate的第三人称单数 )

参考例句：

• A player building a SimCity recapitulates Will Wright's sequence in inventing it. 一位《虚拟城市》玩家总结了威尔发明这个游戏的顺序。 来自互联网
• He hesitates, he recapitulates. 他犹豫不决，颠三倒四。 来自互联网

53 recapitulatory   

adj.概括性的，着重阐述要点的

参考例句：

54 embryos   

n.晶胚；胚，胚胎( embryo的名词复数 )

参考例句：

• Somatic cells of angiosperms enter a regenerative phase and behave like embryos. 被子植物体细胞进入一个生殖阶段，而且其行为象胚。 来自辞典例句
• Evolution can explain why human embryos look like gilled fishes. 进化论能够解释为什么人类的胚胎看起来象除去了内脏的鱼一样。 来自辞典例句