Book IV chapter 9

Milk is formed in the females of all internally viviparous animals, becoming useful for the time of birth. For Nature has made it for the sake of the nourishment¹ of animals after birth, so that it may neither fail at this time at all nor yet be at all superfluous²; this is just what we find happening, unless anything chance contrary to Nature. In the other animals the period of gestation³ does not vary, and so the milk is concocted⁴ in time to suit this moment, but in man, since there are several times of birth, it must be ready at the first of these; hence in women the milk is useless before the seventh month and only then becomes useful. That it is only concocted at the last stages is what we should expect to happen also as being due to a necessary cause. For at first such residual⁵ matter when secreted⁶ is used up for the development of the embryo⁷; now the nutritious⁸ part in all things is the sweetest and the most concocted, and thus when all such elements are removed what remains⁹ must become of necessity bitter and ill-flavoured. As the embryo is perfecting, the residual matter left over increases in quantity because the part consumed by the embryo is less; it is also sweeter since the easily concocted part is less drawn¹⁰ away from it. For it is no longer expended¹¹ on moulding the embryo but only on slightly increasing its growth, it being now fixed¹² because it has reached perfection (for in a sense there is a perfection even of an embryo). Therefore it comes forth¹³ from the mother and changes its mode of development, as now possessing what belongs to it; and no longer takes that which does not belong to it; and it is at this season that the milk becomes useful.

The milk collects in the upper part of the body and the breasts because of the original plan of the organism. For the part above the hypozoma is the sovereign part of the animal, while that below is concerned with nourishment and residual matter, in order that all animals which move about may contain within themselves nourishment enough to make them independent when they move from one place to another. From this upper part also is produced the generative secretion¹⁴ for the reason mentioned in the opening of our discussion. But both the secretion of the male and the catamenia of the female are of a sanguineous nature, and the first principle of this blood and of the blood-vessels is the heart, and the heart is in this part of the body. Therefore it is here that the change of such a secretion must first become plain. This is why the voice changes in both sexes when they begin to bear seed (for the first principle of the voice resides there, and is itself changed when its moving cause changes). At the same time the parts about the breasts are raised visibly even in males but still more in females, for the region of the breasts becomes empty and spongy in them because so much material is drained away below. This is so not only in women but also in those animals which have the mammae low down.

This change in the voice and the parts about the mammae is plain even in other creatures to those who have experience of each kind of animal, but is most remarkable¹⁵ in man. The reason is that in man the production of secretion is greatest in both sexes in proportion to their size as compared with other animals; I mean that of the catamenia in women and the emission¹⁶ of semen in men. When, therefore, the embryo no longer takes up the secretion in question but yet prevents its being discharged from the mother, it is necessary that the residual matter should collect in all those empty parts which are set upon the same passages. And such is the position of the mammae in each kind of animals for both causes; it is so both for the sake of what is best and of necessity.

It is here, then, that the nourishment in animals is now formed and becomes thoroughly¹⁷ concocted. As for the cause of concoction¹⁸, we may take that already given, or we may take the opposite, for it is a reasonable view also that the embryo being larger takes more nourishment, so that less is left over about this time, and the less is concocted more quickly.

That milk has the same nature as the secretion from which each animal is formed is plain, and has been stated previously¹⁹. For the material which nourishes is the same as that from which Nature forms the animal in generation. Now this is the sanguineous liquid in the sanguinea, and milk is blood concocted (not corrupted²⁰; Empedocles either mistook the fact or made a bad metaphor²¹ when he composed the line: ‘On the tenth day of the eighth month the milk comes into being, a white pus’, for putrefaction²² and concoction are opposite things, and pus is a kind of putrefaction but milk is concocted). While women are suckling children the catamenia do not occur according to Nature, nor do they conceive; if they do conceive, the milk dries up. This is because the nature of the milk and of the catamenia is the same, and Nature cannot be so productive as to supply both at once; if the secretion is diverted in the one direction it must needs cease in the other, unless some violence is done contrary to the general rule. But this is as much as to say that it is contrary to Nature, for in all cases where it is not impossible for things to be otherwise than they generally are but where they may so happen, still what is the general rule is what is ‘according to Nature’.

The time also at which the young animal is born has been well arranged. For when the nourishment coming through the umbilical cord is no longer sufficient for the foetus because of its size, then at the same time the milk becomes useful for the nourishment of the newly-born animal, and the blood-vessels round which the so-called umbilical cord lies as a coat collapse²³ as the nourishment is no longer passing through it; for these reasons it is at that time also that the young animal enters into the world.

1 nourishment   

n.食物，营养品；营养情况

参考例句：

• Lack of proper nourishment reduces their power to resist disease.营养不良降低了他们抵抗疾病的能力。
• He ventured that plants draw part of their nourishment from the air.他大胆提出植物从空气中吸收部分养分的观点。

2 superfluous   

adj.过多的，过剩的，多余的

参考例句：

• She fined away superfluous matter in the design. 她删去了这图案中多余的东西。
• That request seemed superfluous when I wrote it.我这样写的时候觉得这个请求似乎是多此一举。

3 gestation   

n.怀孕；酝酿

参考例句：

• The gestation period can be anything between 95 and 150 days.妊娠期从95天至150天不等。
• This film was two years in gestation.这部电影酝酿了两年。

4 concocted   

v.将（尤指通常不相配合的）成分混合成某物( concoct的过去式和过去分词 )；调制；编造；捏造

参考例句：

• The soup was concocted from up to a dozen different kinds of fish. 这种汤是用多达十几种不同的鱼熬制而成的。
• Between them they concocted a letter. 他们共同策划写了一封信。 来自《简明英汉词典》

5 residual   

adj.复播复映追加时间；存留下来的，剩余的

参考例句：

• There are still a few residual problems with the computer program.电脑程序还有一些残留问题。
• The resulting residual chromatism is known as secondary spectrum.所得到的剩余色差叫做二次光谱。

6 secreted   

v.（尤指动物或植物器官）分泌( secrete的过去式和过去分词 )；隐匿，隐藏

参考例句：

• Insulin is secreted by the pancreas. 胰岛素是胰腺分泌的。
• He secreted his winnings in a drawer. 他把赢来的钱藏在抽届里。 来自《简明英汉词典》

7 embryo   

n.胚胎，萌芽的事物

参考例句：

• They are engaging in an embryo research.他们正在进行一项胚胎研究。
• The project was barely in embryo.该计划只是个雏形。

8 nutritious   

adj.有营养的，营养价值高的

参考例句：

• Fresh vegetables are very nutritious.新鲜蔬菜富于营养。
• Hummingbirds have discovered that nectar and pollen are very nutritious.蜂鸟发现花蜜和花粉是很有营养的。

9 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。

10 drawn   

v.拖，拉，拔出；adj.憔悴的，紧张的

参考例句：

• All the characters in the story are drawn from life.故事中的所有人物都取材于生活。
• Her gaze was drawn irresistibly to the scene outside.她的目光禁不住被外面的风景所吸引。

11 expended   

v.花费( expend的过去式和过去分词 )；使用（钱等）做某事；用光；耗尽

参考例句：

• She expended all her efforts on the care of home and children. 她把所有精力都花在料理家务和照顾孩子上。
• The enemy had expended all their ammunition. 敌人已耗尽所有的弹药。 来自《简明英汉词典》

12 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。

13 forth   

adv.向前；向外，往外

参考例句：

• The wind moved the trees gently back and forth.风吹得树轻轻地来回摇晃。
• He gave forth a series of works in rapid succession.他很快连续发表了一系列的作品。

14 secretion   

n.分泌

参考例句：

• Is there much secretion from your eyes?你眼里的分泌物多吗？
• In addition,excessive secretion of oil,water scarcity are also major factors.除此之外，油脂分泌过盛、缺水也都是主要因素。

15 remarkable   

adj.显著的，异常的，非凡的，值得注意的

参考例句：

• She has made remarkable headway in her writing skills.她在写作技巧方面有了长足进步。
• These cars are remarkable for the quietness of their engines.这些汽车因发动机没有噪音而不同凡响。

16 emission   

n.发出物，散发物；发出，散发

参考例句：

• Rigorous measures will be taken to reduce the total pollutant emission.采取严格有力措施，降低污染物排放总量。
• Finally,the way to effectively control particulate emission is pointed out.最后，指出有效降低颗粒排放的方向。

17 thoroughly   

adv.完全地，彻底地，十足地

参考例句：

• The soil must be thoroughly turned over before planting.一定要先把土地深翻一遍再下种。
• The soldiers have been thoroughly instructed in the care of their weapons.士兵们都系统地接受过保护武器的训练。

18 concoction   

n.调配(物)；谎言

参考例句：

• She enjoyed the concoction of foreign dishes.她喜欢调制外国菜。
• His story was a sheer concoction.他的故事实在是一纯属捏造之事。

19 previously   

adv.以前，先前（地）

参考例句：

• The bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
• Let me digress for a moment and explain what had happened previously.让我岔开一会儿，解释原先发生了什么。

20 corrupted   

（使）败坏( corrupt的过去式和过去分词 )； （使）腐化； 引起（计算机文件等的）错误； 破坏

参考例句：

• The body corrupted quite quickly. 尸体很快腐烂了。
• The text was corrupted by careless copyists. 原文因抄写员粗心而有讹误。

21 metaphor   

n.隐喻，暗喻

参考例句：

• Using metaphor,we say that computers have senses and a memory.打个比方，我们可以说计算机有感觉和记忆力。
• In poetry the rose is often a metaphor for love.玫瑰在诗中通常作为爱的象征。

22 putrefaction   

n.腐坏，腐败

参考例句：

• Putrefaction is the anaerobic degradation of proteinaceous materials.腐败作用是蛋白性物质的厌氧降解作用。
• There is a clear difference between fermentation and putrefaction.发酵与腐败有明显区别。

23 collapse   

vi.累倒；昏倒；倒塌；塌陷

参考例句：

• The country's economy is on the verge of collapse.国家的经济已到了崩溃的边缘。
• The engineer made a complete diagnosis of the bridge's collapse.工程师对桥的倒塌做了一次彻底的调查分析。