Chapter 22

In order to understand the way in which the heart is connected with the lung by means of passages, we must consult both dissections and the account in the History of Animals. The universal cause of the need which the animal has for refrigeration, is the union of the soul with fire that takes place in the heart. Respiration¹ is the means of effecting refrigeration, of which those animals make use that possess a lung as well as a heart. But when they, as for example the fishes, which on account of their aquatic² nature have no lung, possess the latter organ without the former, the cooling is effected through the gills by means of water. For ocular evidence as to how the heart is situated³ relatively⁴ to the gills we must employ dissections, and for precise details we must refer to Natural History. As a summarizing statement, however, and for present purposes, the following is the account of the matter.

It might appear that the heart has not the same position in terrestrial animals and fishes, but the position really is identical, for the apex⁵ of the heart is in the direction in which they incline their heads. But it is towards the mouth in fishes that the apex of the heart points, seeing that they do not incline their heads in the same direction as land-animals do. Now from the extremity⁶ of the heart a tube of a sinewy⁷, arterial character runs to the centre where the gills all join. This then is the largest of those ducts, but on either side of the heart others also issue and run to the extremity of each gill, and by means of the ceaseless flow of water through the gills, effect the cooling which passes to the heart.

In similar fashion as the fish move their gills, respiring animals with rapid action raise and let fall the chest according as the breath is admitted or expelled. If air is limited in amount and unchanged they are suffocated⁸, for either medium, owing to contact with the blood, rapidly becomes hot. The heat of the blood counteracts⁹ the refrigeration and, when respiring animals can no longer move the lung aquatic animals their gills, whether owing to discase or old age, their death ensues.

1 respiration   

n.呼吸作用；一次呼吸；植物光合作用

参考例句：

• They tried artificial respiration but it was of no avail.他们试做人工呼吸，可是无效。
• They made frequent checks on his respiration,pulse and blood.他们经常检查他的呼吸、脉搏和血液。

2 aquatic   

adj.水生的，水栖的

参考例句：

• Aquatic sports include swimming and rowing.水上运动包括游泳和划船。
• We visited an aquatic city in Italy.我们在意大利访问过一个水上城市。

3 situated   

adj.坐落在...的，处于某种境地的

参考例句：

• The village is situated at the margin of a forest.村子位于森林的边缘。
• She is awkwardly situated.她的处境困难。

4 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。

5 apex   

n.顶点，最高点

参考例句：

• He reached the apex of power in the early 1930s.他在三十年代初达到了权力的顶峰。
• His election to the presidency was the apex of his career.当选总统是他一生事业的顶峰。

6 extremity   

n.末端，尽头；尽力；终极；极度

参考例句：

• I hope you will help them in their extremity.我希望你能帮助在穷途末路的他们。
• What shall we do in this extremity?在这种极其困难的情况下我们该怎么办呢？

7 sinewy   

adj.多腱的，强壮有力的

参考例句：

• When muscles are exercised often and properly,they keep the arms firm and sinewy.如果能经常正确地锻炼肌肉的话，双臂就会一直结实而强健。
• His hard hands and sinewy sunburned limbs told of labor and endurance.他粗糙的双手，被太阳哂得发黑的健壮四肢,均表明他十分辛勤，非常耐劳。

8 suffocated   

（使某人）窒息而死( suffocate的过去式和过去分词 )； （将某人）闷死； 让人感觉闷热； 憋气

参考例句：

• Many dogs have suffocated in hot cars. 许多狗在热烘烘的汽车里给闷死了。
• I nearly suffocated when the pipe of my breathing apparatus came adrift. 呼吸器上的管子脱落时，我差点给憋死。

9 counteracts   

对抗，抵消( counteract的第三人称单数 )

参考例句：

• The drug counteracts the effects of the poison. 这种药可抵消毒物的作用。
• Offset Something that balances, counteracts, or compensates the effects of another thing. 弥补用来平衡、抵消或偿还另一财物的东西。