relation between the nervous and sanguiferous systems. 429 
produce any excitement in the muscles of voluntary motion, 
both chemical and mechanical stimuli still increased the 
action of the heart ; the former more than the latter. 
Exp. 6. I tried, in every possible way, both by mechanical 
and chemical stimuli, and both before and after the sensibility 
was destroyed, to excite, through the brain or spinal marrow 
of rabbits and frogs, any irregular action in the heart which 
is so readily excited in the muscles of voluntary motion, but 
could not. Nor could I by sedatives, applied to the nervous 
system, occasion any irregular action in it. Its action was 
rendered quicker or slower, more or less frequent, stronger 
or weaker, but never irregular. The only instance in which 
irregular action was excited in the heart, was when its power 
was nearly destroyed by crushing the brain or spinal marrow. 
Exp. 7. I found from many trials both on rabbits and 
frogs, that the excitement of the muscles of voluntary motion 
took place chiefly at the time the stimulus was applied to the 
brain or spinal marrow. It was generally necessary to move 
the instrument; thus applying it to a new surface in order to 
support the effect. The repeated-contractions of the muscles 
of voluntary motion will sometimes continue, assuming the 
form of a fit, as long as the instrument remains in the brain, 
although it be kept as still as the motions of the animal will 
admit of. The increased action of the heart on the contrary, 
continued as long as the stimulus, whether chemical or 
mechanical, was applied, unless it was of a nature to produce 
the sedative, after the stimulant effect. The sedative effect 
was so far from being the consequence of the previous excite- 
ment, as many physiologists have supposed, that spirit of 
wine and mechanical stimuli, which produced no sedative 
