iBS Mr. Brodie on the different Modes 
ceased to respire ; and this was confirmed by another experi- 
ment, in which, in a dog killed by the infusion of tobacco, I 
found the cavities of the left side of the heart to contain scarlet 
blood, while in those of the right side the blood was dark 
coloured. This poison therefore differs materially from alco- 
hol, the essential oil of almonds, and the juice of aconite, which 
have no direct influence on the action of the heart. The infu- 
sion of tobacco renders the heart insensible to the stimulus of 
the blood, but it does not altogether destroy the power of 
muscular contraction, since the heart resumed its action in one 
instance on the division of the pericardium, and I have found 
that the voluntary muscles of an animal killed by this poison, 
are as readily stimulated to contract by the influence of the 
Voltaic battery, as if it had been killed in any other manner. 
At the same time, however, that the infusion of tobacco de- 
stroys the action of the heart, it appears to destroy also the 
functions of the brain, since these did not return in the last 
experiment ; although the circulation was restored, and kept 
up by artificial respiration. 
Since there is no direct communication between the intes- 
tinal canal and the heart, I was at first induced to suppose 
that the latter becomes affected in consequence of the infusion 
being conveyed into the blood by absorption. Some circum- 
stances in the following experiment have since led me to doubt 
whether this is the case. 
Exp. 12. In a dog, whose head was removed, I kept up the 
circulation by means of artificial respiration, in the manner 
already described in the account of some experiments, which 
I lately, communicated to this Society. I then injected into 
the stomach and intestines nine ounces of infusion of tobacco, 
