Chapter 7

A few of the previous physical philosophers have spoken of respiration¹. The reason, however, why it exists in animals they have either not declared or, when they have, their statements are not correct and show a comparative lack of acquaintance with the facts. Moreover they assert that all animals respire-which is untrue. Hence these points must first claim our attention, in order that we may not be thought to make unsubstantiated charges against authors no longer alive.

First then, it is evident that all animals with lungs breathe, but in some cases breathing animals have a bloodless and spongy lung, and then there is less need for respiration. These animals can remain under water for a time, which relatively² to their bodily strength, is considerable. All oviparous animals, e.g. the frog-tribe, have a spongy lung. Also hemydes and tortoises can remain for a long time immersed in water; for their lung, containing little blood, has not much heat. Hence, when once it is inflated³, it itself, by means of its motion, produces a cooling effect and enables the animal to remain immersed for a long time. Suffocation⁴, however, always ensues if the animal is forced to hold its breath for too long a time, for none of this class take in water in the way fishes do. On the other hand, animals which have the lung charged with blood have greater need of respiration on account of the amount of their heat, while none at all of the others which do not possess lungs breathe.

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 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。

3 inflated   

adj.（价格）飞涨的；（通货）膨胀的；言过其实的；充了气的v.使充气（于轮胎、气球等）( inflate的过去式和过去分词 )；（使）膨胀；（使）通货膨胀；物价上涨

参考例句：

• He has an inflated sense of his own importance. 他自视过高。
• They all seem to take an inflated view of their collective identity. 他们对自己的集体身份似乎都持有一种夸大的看法。 来自《简明英汉词典》

4 suffocation   

n.窒息

参考例句：

• The greatest dangers of pyroclastic avalanches are probably heat and suffocation. 火成碎屑崩落的最大危害可能是炽热和窒息作用。 来自辞典例句
• The room was hot to suffocation. 房间热得闷人。 来自辞典例句