i88 Transactions of the Canadian Institute. [Vol. VII. 



spaniel, weighing about 40 lbs., had been given three-quarters of a grain 

 of morphia an hour before the experiment began. It then was chloro- 

 formed. After it was completely insensible and for several minutes had 

 not been taking any more of the anaesthetic, this fall in pressure 

 occurred. It looked somewhat like that produced by irritation of the 

 vagus nerve, and it was suggested that the canula in the left carotid 

 might be producing this, but nothing was altered and yet the pressure 

 recovered of itself and the fall did not recur during the two-hour 

 experiment. 



AAnAAATUUiATuviAnnnTinAJvviAnnAruvuTAruuuinju^^ 



Tracing II. — 3/7. — Dog under Morphia. No Chloroform for several minutes. Shows marked fall in 

 pressure with slowing of pulse. Animal horizontal. Cnuse of fall not apparent and it was spontaneously 

 recovered from. 



Tracing 2 shows another fall occurring under similar circumstances 

 to the last. The animal had not had any chloroform for several minutes. 

 In this case the fall is even more marked, and looks extremely like that 

 produced by irritation of the vagus, but it completely disappeared 

 without any of the factors having been altered, and did not recur. 



Such falls as these, when they happen to occur during the actual 

 administration of chloroform, may be the unexpected ones described by 

 the Glasgow Commission on Chloroform, and which Lieut.-Col. Lawrie 

 ascribed to asphyxia ; we will refer to this point later on. 



It was frequently noted how much different dogs varied as regards 

 the amount of their blood pressure and pulse rate. Often poorly- 

 nourished and small varieties of dogs had high pressures, whilst large, 

 well-nourished animals had the opposite. 



