204 



Transactions of the Canadian Institute. 



[Vol. VII. 



There can be no doubt but that chloroform 

 can weaken and even paralyse the heart, and that 

 chloroform can weaken and even paralyze the 

 vaso-motor centre, but the question at issue is, 

 which of these two actions is it that occurs first. 

 In my opinion it would be exceedingly unlikely 

 if either one should occur alone, and the proba- 

 bilities are that the fall in pressure is due to both 

 factors occurring in different degrees in different 

 animals. In one case the vaso-motor centre might 

 prove the more susceptible to the poison, while in 

 another the heart might first show its effects. In 

 both cases a fall in pressure would occur. 



The importance of the fall is very differently 

 guaged by different observers. As already stated, 

 all have noticed it. The Hyderabad Commission 

 actually considered it a safeguard, arguing that 

 where the pressure was low less chloroform would 

 be carried to the centres, and therefore these were 

 not so likely to be poisoned ; and J. A. Mc- 

 VVilliam argued in the same manner.' On the 

 other hand Mr. Leonard Hill thinks that this fall 

 in pressure, due in his opinion to paralysis of the 

 vaso-motor centre by chloroform, is actually the 

 cause of death in such cases, and he believes that 

 the respiratory failure which occurs so constantly 

 in dogs poisoned by chloroform is due to the 

 anaemia of the respiratory centre resulting from 

 a fall in pressure. Without venturing to express 

 an opinion on so important a point one may say 

 that a mere fall of blood pressure with assumed 

 anaemia of the respiratory centre does not soon 

 cause stoppage of the respiration but rather 

 stimulates it, as shown in Tracing 21, where the 

 animal was bled to death and the respiration 

 continued even after the blood had ceased to flow 

 from the severed vessel. H. C. Woods and 

 W. S. Carter'- have shown that even great 



1 British Medical Journal, 1890, Vol. II. p.834. 



2 Journal of Experimental Medicine, Vol. II, p. 130. 



