1872.] The Physiological Positicn of Tobacco. 483 
pulse was at 120. Section of the pneumogastric nerve ir- 
creased the beats to 210, but the injection of 0°004 m.grm. 
of nicotine into the abdomen, whilst producing the usual 
symptoms of poisoning, had no influence upon the circu- 
lation. In a terrier dog, poisoned with 0°003 m.grm. of 
nicotine, the pulse rose from 104 to Igo beats, and the 
exposure of the pneumogastric nerve to the action of gal- 
vanism did not diminish them. ‘Thus the increase of the 
heart’s action, caused by tobacco, results from its paralysing 
effect upon the pneumogastric nerve. The increase in pres- 
sure he considers due, first, to the quickened heart-beat, and 
secondly, to the paralysing influence of tobacco upon the 
splanchnic nerve, which is to the vascular system what the 
par vagum is to the heart. In small doses it increases the 
excitability of these nerves; in large doses it diminishes it, 
and that in proportion to their extent. The secondary 
effect of this is to augment the arterial pressure and heart- 
beats, and to contract the muscles of the vessels. 
The vertigo and trembling noticed in animals poisoned 
by tobacco are owing to the smaller calibre of the blood- 
vessels, consequent upon the contraction of their walls pro- 
duced by nicotine. 
Blatin also endeavoured to ascertain the effects of tobacco 
upon respiration. A small dog, making 16 respirations per 
minute, was pricked ten times in the abdomen with a needle 
dipped in an aqueous solution of nicotine; the effect was, 
in five minutes, to increase the breathings to 38. Three 
days after, a drop of pure nicotine was introduced into 
a wound made on the inside of the leg. In an instant 
the respirations rose from 16 to 25, another moment saw 
them rise to 38; they then began to decrease, and in five 
minutes had fallen to 12. Two more drops were now placed 
on the wound; the breathings descended from I1 to Io, 
then to g, stood five minutes at 8, and then another drop of 
nicotine reduced them to 4. The respiration was now quite 
irregular. Section of the pneumogastric caused no change, 
and in a quarter of an hour the animal died. From this it 
is clear that a small dose of nicotine accelerates, whilst 
a large one progressively diminishes them. Section of 
the pneumogastric produces the same effect as a strong 
dose of nicotine. A small dose accelerates the respiration, 
even after the section of the par vagum. This will be 
caused by its action upon the spinal cord. Strong doses 
cause the same paralysing action we have already noticed 
acting upon the circulation. 
Blatin was struck with the diminution or destruction of 
