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II, The Croonian Lecture , on some Physiological Researches, respect- 
mg the Influence of the Brain on the Action of the Heart , and on 
the Generation of animal Heat. By Mr. B. C. Brodie, F.R.S. 
Head December 20, 1810. 
Having had the honour of being appointed, by the President 
of the Royal Society, to give the Croonian Lecture, I trust that 
the following facts and observations will be considered as tend- 
ing 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 conti- 
nuance 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 how far the 
influence of the brain is necessary to the action of the heart, I 
found that when an animal was pithed by dividing the spinal 
marrow in the upper part of the neck, respiration was imme- 
diately destroyed, but the heart still continued to contract cir- 
culating dark-coloured blood, and that in some instances from 
ten to fifteen minutes elapsed before its action had entirely 
ceased. I further found that when the head was removed, 
the divided blood vessels being secured by a ligature, the 
circulation still continued, apparently unaffected by the entire 
separation of the brain. These experiments confirmed the 
