396 



Dr. E. H. Embley. 



[June 13, 



The heart rate increased in some experiments, but it will be noticed, on 

 reference to the tracings, that in the experiments with stronger mixtures 

 the rate slowed after the administration had been discontinued. 



In subsequent experiments on the intact animal, with natural respira- 

 tion, it appeared impossible to introduce sufficient ethyl chloride into the 

 circulation by inhalation to produce the above rapid paralysis of heart 

 muscle, as cessation of respiration or vagus inhibition of the heart occurred to 

 check further intake. 



Conclusions. — The effect of ethyl chloride upon heart muscle, as in the case 

 with chloroform and in contrast with that of ether, is paralytic, but the 

 quantity of ethyl chloride vapour in the air required is 19 times as great 

 as that of chloroform to produce comparable results. 



Effect of Ethyl Chloride upon the Vascular System. 

 This investigation was approached in three ways : — 



(1) By investigating the effects of ethyl chloride upon the arterioles 

 independent of the central vaso-motor system. 



(2) By investigating its effect upon the central vaso-motor mechanism. 



(3) By investigating the resultant of its combined action on the vessels 

 and on the vaso-motor system in the intact animal. 



(1) The Effect of Ethyl Chloride upon the Arterioles. 



This was accomplished by measuring the changes in the outflow, under 

 constant pressure, of blood circulating through a loop of excised bowel 

 together with the isolated lungs of the animal. The method employed was 

 that described, in a similar research in connection with chloroform, by 

 Embley and Martin (6). 



After sufficient time had been allowed for the circulatory flow to become 

 constant, air containing 30 per cent, of ethyl chloride vapour was pumped 

 into the lungs. The curve, fig. 5, was plotted from the tracing which 

 recorded the drop-rate, the time, and the pressure. The ordinates represent 

 the number of drops per minute against time in minutes along the abscissae. 

 The and 8 perpendicular lines indicate the time during which the 

 anaesthetic was administered. The pressure at which the blood circulated 

 was 80 mm. Hg throughout. 



The ethyl chloride was administered during 8 minutes, and it will be seen 

 that, following upon the introduction of the ethyl chloride into the respired air, 

 a gradual increase in flow occurred which continued after the administration 

 had ceased. The maximum effect was a 50"5 per cent, increase. This rate 



