y6 Dr. Philip's experimmts to ascertain the principle 
brain and spinal marrow, and opened the chest. The heart 
was found contracting with vigour. Spirit of wine was then 
applied to the spinal marrow, with an immediate and evident 
increase of the action of the heart. It was then applied to the 
brain with the same effect. Watery solutions of opium and 
tobacco were also applied to both, with precisely the same 
effect as in the rabbit. The increase of action from the opium 
and tobacco was much less than from the spirit of wine, and 
was soon followed by a great diminution of action. The in- 
crease of action was least, and the diminution greatest from 
tobacco. On washing off the opium and tobacco with a wet 
sponge, the heart immediately beat more strongly. The diffe- 
rent parts of this experiment were frequently repeated with 
the same result. It is remarkable that we could affect the 
motion of the heart by stimuli applied to the brain and spinal 
marrow, after they had ceased to produce any effect on the 
muscles of voluntary motion through the medium of the ner- 
vous system. 
Exp. 16. This experiment only differed from the last jn the 
-cervical part of the spinal marrow and lower part of the brain 
being removed, and the stimuli applied only to that part of 
the brain which lies between the eyes of the frog. Spirit of 
wine, opium, and tobacco, thus applied, affected the motion of 
the heart quite as much, and precisely in the same way, as 
when they were applied to the entire brain and spinal mar- 
row. When opium and tobacco were applied to the lower 
part of the spinal marrow, the motion of the heart appeared 
to be hardly at all affected by them. It was evidently in- 
creased when spirit of wine was applied to the same part. 
We found in the foregoing experiments, that considerable 
