WHICH SUBSISTS BETWEEN THE RESPIRATION AND IRRITABILITY. 329 
It was shown by Hook, in the early days of the Royal Society*, that if, 
the respiration being suspended, an animal appeared to be dying, the beat 
of the heart and the signs of life were speedily restored, on performing arti- 
ficial respiration, or even by forcing air through the trachea, bronchia, and 
pulmonary air-cells and allowing it to escape through incisions made through 
the pleura. 
It was, in the next place, clearly shown by Goodwyn, in one of the most 
beautiful specimens of physiological inquiry in any language*!', ^ at i n sus- 
pended respiration, it is the left side of the heart which first ceases to contract, 
the right side still continuing its function for several minutes, until the sup- 
ply of blood may be supposed to fail. 
The facts detailed by Harvey had shown that the left side of the heart was 
endued with less irritability than the right ; the experiment of Hook, that re- 
spiration restored the action of the heart, if it had previously ceased ; that of 
Goodwyn, that this cessation and restoration of functions were observed in 
the left side of the heart. It was obvious, on the other hand, that the re- 
spiration belongs, as it were, to the left side of the heart. 
It appears plainly deducible from these facts, that in circumstances and 
structures the most similar, the respiration is accurately inversely as the irri- 
tability. 
For the sake of a comparison with the hybernating animal, the object of 
which will be explained hereafter, I thought it right to repeat this experi- 
ment. 
Before I proceed to detail the result, I may just describe an easy method of 
performing that part of it which consists of artificial respiration. A quill is 
firmly fixed in the divided trachea; a small hole is then cut into that part of the 
quill which is external ; Read’s syringe is then adapted to the other end of 
the quill. At each motion of the piston downwards, the lungs are distended ; 
whilst the piston is raised, the air escapes through the opening in the quill, pro- 
ducing expiration. The experiment, therefore, only requires the common ac- 
tion of the syringe. 
The experiment itself answered my expectation. During the cessation of 
* Phil. Trans, vol. ii. 
t On the Connexion of Life with Respiration : London, 1788, pp. 72, 82 note. 
