relation between the nervous and sanguiferous systems. 431 
dent of the nervous system, and whether they are directly 
influenced by that system, or only through the medium of 
the heart. 
It appeared to me probable, from many experiments, that 
the cause of chemical stimuli, applied to the nervous system, 
producing a greater effect on the heart than mechanical 
stimuli do, is, that the former from their nature act on a 
larger portion of the brain and spinal marrow. If this 
opinion is correct, the mechanical stimulus will be rendered 
the most powerful by confining the chemical to a smaller 
space than the mechanical stimulus occupies. 
Exp. 8. Both in frogs and rabbits I applied to various 
parts of the brain and spinal marrow, and particularly to 
those parts from which the nerves originate, minute portions 
of strong spirit of wine, without at all influencing the action 
of the heart. When these small portions were applied to a 
great many parts, the heart began to beat more frequently. 
This of course was much the same thing as at once applying 
the spirit of wine to a larger part. We have seen in the fore- 
going experiments, that mechanical stimuli applied to any 
considerable portion of the nervous system, increase the 
action of the heart. It appears from the following experi- 
ments that we cannot affect the heart by mechanical stimuli 
confined to any small part either of the brain or spinal 
marrow. 
Exp. g. In a rabbit deprived of sensibility by a blow on the 
occiput, I wounded different small parts of the brain with a 
wire, particularly all those parts near which the nerves of the 
heart appear chiefly to originate; but could not affect the 
motion of this organ, while at the same time passing the wire 
