INFLUENCE OF THE BRAIN ON TKE ACTION OP THE HEART. 360 



2. When the brain is injured or removed, the action of 

 the heart ceases, only because respiration is under its in- 

 fluence, and if under these circumstances respiration is ar. 

 ficially produced, the circulation will still continue. 



3. When the influence of the brain is cut off, the se- 

 cretion of urine appears to cease, and no heat is gene- 

 rated; notwithstanding the functions of respiration and 

 the circulation of the blood continue to be performed, and 

 the usual changes in the appearance of the blood are pro- 

 duced in the lungs. 



4. When the air respired is colder than the natural tem- 

 perature of the animal, the effect of respiration is not to 

 generate, but to diminish animal heat. 



AddUton to the Croonian Lecture for the Year 1810. 

 (P. 207.) 



In the experiments above detailed, where the circulation Artificial re- 

 was maintained by means of artificial respiration after the ^P'^J^'^!J^^[^* 

 head was removed, 1 observed that the blood, in its pas- changes on the« 

 s.age through the lungs, was altered from a dark to a^^^°°^^J^"^ 

 scarlet colour; and h(;nce I was ted to conclude, that the 

 action of the air produced in it changes analogous to those, 

 ivhich occur under ordinary circumstances. I have lately, ' 



with i\\e assistance of my friend Mr. W. Brande, made the 

 following experiment, which appears to confirm the truth 

 of this conclusion. 



Ati elastic gum bottle, having a tube and stop-cock con- Experiment to 

 nected with it, was filled with about a pint of oxigen gas. ^^^°^^ '^"^* 

 The spinal marrow was divided in the neck of a young 

 rabbit, and, the blood vessels having been secured, the head 

 was removed, and the circulation was maintained by in- \ 



flating the lungs with atmosphelic air for five minutes, at 

 the end of w hich time the tube of the gum bottle was in- 

 serted into the trachea, and carefully secured by a ligature,- 

 so that no air might escape. By making pressure on the 

 gum bottle, the gas was made to pass and repass into and 

 from the lungs about thirty times in a minute. At first, 

 the heart acted one hundred and twenty times in a minute, 

 with regularity and strength ; tho thermometer, in the rec- ' 



turn, rose to 100^. At the end of an hour, the heart 

 acted as frequently as before, but more feebly; the blood 



Vol, XXIX,— SupPLEME^'T. D b in 



