INFLUENCE OP THE BRAIN ON Tttt ACTION Of THfi ttti-RT, 359 



VIII. 



The Croonian Lecture^ on some Physiological Researches^ 

 respecting the Influence of the Brain on the Action of 

 the Hearty and on the Generation of animal Heat, By 

 Mr, B. C. BiioDiE, F. R. S. * 



JlIaVING had the honour of being appointed, by the pre- Influenceof 



.1 i. 1 T» I n . i . . ji /^ • 1 i the brain on 



sident of the Koyal Society, to give the Lroonian lecture, ^^e action of 



I trust, that the following facts and observations will be the heart. 

 considered as tending sufficiently to promote the objects, 

 for which the lecture was instituted. They appear to 

 throw some light on the mode, in which the influence of 

 the brain is necessary to the continuance of the action of 

 the heart ; and on the effect which the changes produced 

 on the blood in respiration have on the heat of the animal 

 body. 



In making experiments on animals to ascertain ftow far Not directly ne- 

 the influence of the brain is necessary to the action of the 

 heart, I found, that, when an animal was pithed by di- 

 viding the spinal marrow on the upper part of the neck, 

 respiration was immediately destroyed, but the heart still 

 continued to contract circulating dark coloured blood ; and 

 that in some instances from ten to fifteen minutes elapsed, 

 before its action had entirely ceased. I farther found, that, 

 when the head was removed, the divided blood vessels 

 being secured by a ligature, the circulation still continued, 

 apparently unafiected by the entire separation of the brain. 

 These experiments confirmed the observation of Mr. Cruick* 

 fihank + and Mr. Bichat J, that the brain is not directly ne- 

 cessary to the action of the heart; and that,' when the 

 functions of the brain are destroyed, the circulation ceases 

 only in consequence of the suspension of the respiration. 

 This led me to conclude, that, if respiration was produced 

 artificially, the heart would continue to contract for a 

 ^till longer period of time after the removal of the braii^. 



* Philos. Trans, for 1811, p. 36, 



f Philosophical Transactions 1795. 



J Recherches Physrologiques suf la Vie et la Mort. 



