98 



same time, several small punctures through the outer 

 coat of the lungs. By blowing in a stream of fresh 

 air, which continued to escape through the small 

 apertures made in the lungs, he was enabled to keep 

 those organs fully distended. As long as he sup- 

 plied the lungs with air, the actions of life continued, 

 and the heart beat very regularly ; but, on intermit- 

 ting the supply, the dog would immediately fall into 

 dying convulsive fits, and revive again as soon as 

 the lungs were filled with a stream of fresh air. The 

 circulation through the lungs continued both during 

 their distended and collapsed state, and as well when 

 they were kept at rest, as during a state of motion : 

 whence he concluded, that neither the motion of the 

 lungs, nor the cessation of their motion, nor the 

 stopping of the circulation of the blood through them, 

 was the immediate cause of death, but the want of 

 a sufficient supply of fresh air *. By the researches 

 of later philosophers, it has been proved, that the 

 air, in all animals, serves the same uses"; to fit it for 

 which, it undergoes the same changes. In our in- 

 quiry into the nature of these changes, the manner 

 in which they are effected, and the uses which" they 

 are found to serve, we shall confine ourselves chiefly 

 to the facts which take place in human respiration, 

 not only on account of their greater interest, but 

 also because they have occupied more research, and, 

 having been more frequently submitted to experi- 

 ment, are in some respects better ascertained. 



* Lowthorpe's Abrid. Phil. Trans, vol. iii. p. 6G. 



