Action of Tobacco Smoke 



:341 



Ringer's solution was employed as the perfusing fluid. All three drugs 

 reduce the flow through the vessels if in sufficient concentration, but this 

 result is not obtained with dilute solutions such as 1 in 10,000. It is 

 known that nicotine solutions of this dilution constrict blood-vessels in an 

 intact animal to a very decided degree ; all that these experiments there- 

 fore show is that nicotine in dilute solutions does not act directly on the 

 vessel wall. 



Collidine and pyridine, in doses which one may regard as possible in 

 man, have practically no action upon the blood-vessels. 



Signal 



Signal 



Fig. 3. — Isolated rabbit's heuit perfused b) La nge iid or f f ' s method. 



A shows the effect of injecting into the lateral tube 3 c.o. of the smoke solution, and U, 2 c.c. 

 of 1 per cent, solution of nicotine. Time, 1 cm. = 10 seconds. 



iv. The Eflect of Intravenous Injection of the Constituents of 

 Tobacco Smoke, (a) On the Spinal Cord. — Small doses of these drugs 

 injected directly into the circulation of rabbits excite the spinal cord, and 

 if the doses be sufficiently large, convulsions are produced. These convulsive 

 movements diff"er from those produced by strychnine in that there is no 

 antecedent tonic stage ; the animal passes into a condition of anaesthesia 

 associated witli clonic contractions of all the muscles supplied by the spinal 

 cord. This effect is much the most marked with nicotine ; it is very small 

 in the ca.ses of collidine and pyridine. That the convulsions are spinal in 

 origin may be shown by painting the spinal cord of a decapitated frog with 

 the drug, when the muscles supplied by that part will be observed to 



