Chapter XII

That There is a Circulation of the Blood is Shown from the Second Position Demonstrated

If these things be so, another point which I have already referred to, viz., the continual passage of the blood through the heart will also be confirmed. We have seen, that the blood passes from the arteries¹ into the veins³, not from the veins into the arteries; we have seen, farther, that almost the whole of the blood may be withdrawn⁴ from a puncture⁶ made in one of the cutaneous veins of the arm if a bandage properly applied⁷ be used; we have seen, still farther, that the blood flows so freely and rapidly that not only is the whole quantity which was contained in the arm beyond the ligature, and before the puncture was made, discharged, but the whole which is contained in the body, both that of the arteries and that of the veins.

Whence we must admit, first, that the blood is sent along with an impulse, and that it is urged with force below the ligature; for it escapes with force, which force it receives from the pulse and power of the heart; for the force and motion of the blood are derived⁸ from the heart alone. Second, that the afflux proceeds from the heart, and through the heart by a course from the great veins; for it gets into the parts below the ligature through the arteries, not through the veins; and the arteries nowhere receive blood from the veins, nowhere receive blood save and except from the left ventricle of the heart. Nor could so large a quantity of blood be drawn⁵ from one vein² (a ligature having been duly applied), nor with such impetuousity, such readiness, such celerity, unless through the medium of the impelling⁹ power of the heart.

But if all things be as they are now represented, we shall feel ourselves at liberty to calculate the quantity of the blood, and to reason on its circular motion. Should anyone, for instance, performing phlebotomy, suffer the blood to flow in the manner it usually does, with force and freely, for some half hour or so, no question but that the greatest part of the blood being abstracted, faintings and syncopes would ensue, and that not only would the arteries but the great veins also be nearly emptied of their contents. It is only consonant¹⁰ with reason to conclude that in the course of the half hour hinted at, so much as has escaped has also passed from the great veins through the heart into the aorta¹¹. And further, if we calculate how many ounces flow through one arm, or how many pass in twenty or thirty pulsations under the medium ligature, we shall have some grounds for estimating how much passes through the other arm in the same space of time: how much through both lower extremities¹², how much through the neck on either side, and through all the other arteries and veins of the body, all of which have been supplied with fresh blood, and as this blood must have passed through the lungs and ventricles of the heart, and must have come from the great veins, we shall perceive that a circulation is absolutely necessary, seeing that the quantities hinted at cannot be supplied immediately from the ingesta, and are vastly more than can be requisite¹³ for the mere¹⁴ nutrition of the parts.

It is still further to be observed, that in practising phlebotomy the truths contended for are sometimes confirmed in another way; for having tied up the arm properly, and made the puncture duly, still, if from alarm or any other causes, a state of faintness supervenes, in which the heart always pulsates¹⁵ more languidly, the blood does not flow freely, but distils¹⁶ by drops only. The reason is, that with a somewhat greater than usual resistance offered to the transit¹⁷ of the blood by the bandage, coupled with the weaker action of the heart, and its diminished impelling power, the stream cannot make its way under the ligature; and farther, owing to the weak and languishing¹⁸ state of the heart, the blood is not transferred in such quantity as wont¹⁹ from the veins to the arteries through the sinuses of that organ. So also, and for the same reasons, are the menstrual fluxes²⁰ of women, and indeed hemorrhages of every kind, controlled. And now, a contrary state of things occurring, the patient getting rid of his fear and recovering his courage, the pulse strength is increased, the arteries begin again to beat with greater force, and to drive the blood even into the part that is bound; so that the blood now springs from the puncture in the vein, and flows in continuous stream.

1 arteries   

n.动脉( artery的名词复数 )；干线，要道

参考例句：

• Even grafting new blood vessels in place of the diseased coronary arteries has been tried. 甚至移植新血管代替不健康的冠状动脉的方法都已经试过。 来自《简明英汉词典》
• This is the place where the three main arteries of West London traffic met. 这就是伦敦西部三条主要交通干线的交汇处。 来自《简明英汉词典》

2 vein   

n.血管，静脉；叶脉，纹理；情绪；vt.使成脉络

参考例句：

• The girl is not in the vein for singing today.那女孩今天没有心情唱歌。
• The doctor injects glucose into the patient's vein.医生把葡萄糖注射入病人的静脉。

3 veins   

n.纹理；矿脉( vein的名词复数 )；静脉；叶脉；纹理

参考例句：

• The blood flows from the capillaries back into the veins. 血从毛细血管流回静脉。 来自《简明英汉词典》
• I felt a pleasant glow in all my veins from the wine. 喝过酒后我浑身的血都热烘烘的，感到很舒服。 来自《简明英汉词典》

4 withdrawn   

vt.收回；使退出；vi.撤退，退出

参考例句：

• Our force has been withdrawn from the danger area.我们的军队已从危险地区撤出。
• All foreign troops should be withdrawn to their own countries.一切外国军队都应撤回本国去。

5 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。

6 puncture   

n.刺孔，穿孔；v.刺穿，刺破

参考例句：

• Failure did not puncture my confidence.失败并没有挫伤我的信心。
• My bicycle had a puncture and needed patching up.我的自行车胎扎了个洞，需要修补。

7 applied   

adj.应用的；v.应用，适用

参考例句：

• She plans to take a course in applied linguistics.她打算学习应用语言学课程。
• This cream is best applied to the face at night.这种乳霜最好晚上擦脸用。

8 derived   

vi.起源；由来；衍生；导出v.得到( derive的过去式和过去分词 )；（从…中）得到获得；源于；（从…中）提取

参考例句：

• Many English words are derived from Latin and Greek. 英语很多词源出于拉丁文和希腊文。 来自《简明英汉词典》
• He derived his enthusiasm for literature from his father. 他对文学的爱好是受他父亲的影响。 来自《简明英汉词典》

9 impelling   

adj.迫使性的，强有力的v.推动、推进或敦促某人做某事( impel的现在分词 )

参考例句：

• Impelling-binding mechanism is the micro foundation of venture capital operation. 激励约束机制是创业投资运作的微观基础。 来自互联网
• Impelling supervision is necessary measure of administrative ethic construction. 强有力的监督是行政伦理建设的重要保证。 来自互联网

10 consonant   

n.辅音；adj.[音]符合的

参考例句：

• The quality of this suit isn't quite consonant with its price.这套衣服的质量和价钱不相称。
• These are common consonant clusters at the beginning of words.这些单词的开头有相同辅音组合。

11 aorta   

n.主动脉

参考例句：

• The abdominal aorta is normally smaller than the thoracic aorta.腹主动脉一般比胸主动脉小。
• Put down that jelly doughnut and look carefully at this aorta.放下手头上的东西，认真观察这张大动脉图片。

12 extremities   

n.端点( extremity的名词复数 )；尽头；手和足；极窘迫的境地

参考例句：

• She was most noticeable, I thought, in respect of her extremities. 我觉得她那副穷极可怜的样子实在太惹人注目。 来自辞典例句
• Winters may be quite cool at the northwestern extremities. 西北边区的冬天也可能会相当凉。 来自辞典例句

13 requisite   

adj.需要的，必不可少的；n.必需品

参考例句：

• He hasn't got the requisite qualifications for the job.他不具备这工作所需的资格。
• Food and air are requisite for life.食物和空气是生命的必需品。

14 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。

15 pulsates   

v.有节奏地舒张及收缩( pulsate的第三人称单数 )；跳动；脉动；受（激情）震动

参考例句：

• My life pulsates with every movment of my country. 我的一生是随着祖国的脉搏而跳动的。 来自辞典例句
• The sick cow frequently attempts urination and pulsates the urethra over the ischium arch. 病牛频频企图排尿，搏动坐骨弓上的尿道。 来自辞典例句

16 distils   

v.蒸馏( distil的第三人称单数 )；从…提取精华

参考例句：

• A proverb distils the wisdom of ages. 谚语是许多世纪智慧的精华。 来自辞典例句
• The cool of the night distils the dew. 清凉的夜晚洒落露水。 来自互联网

17 transit   

n.经过，运输；vt.穿越，旋转；vi.越过

参考例句：

• His luggage was lost in transit.他的行李在运送中丢失。
• The canal can transit a total of 50 ships daily.这条运河每天能通过50条船。

18 languishing   

a. 衰弱下去的

参考例句：

• He is languishing for home. 他苦思家乡。
• How long will she go on languishing for her red-haired boy? 为想见到她的红头发的儿子，她还将为此烦恼多久呢？

19 wont   

adj.习惯于；v.习惯；n.习惯

参考例句：

• He was wont to say that children are lazy.他常常说小孩子们懒惰。
• It is his wont to get up early.早起是他的习惯。

20 fluxes   

连续的改变( flux的名词复数 )； 不稳定的状态； 不停的变化； 通量

参考例句：

• In general, fluxes and forces may have different tensorial characters. 一般说来，力和通量可以具有不同的张量特征标。
• The parameterized eddy fluxes simulatedthe seasonal and latitudinal variations reasonably well. 模拟出涡动通量的空间分布和时间变化。