ON THE PHYSIOLOGICAL ACTION OF THE METHYL COMPOUNDS. 175 
Influence on the Circulation and Respiration. 
I have studied as a special point the influence of certain of the ethyls and 
methyls, with a view to determine the all-important subject of their relative 
action, upon the respiration and the circulation. On this point there has been 
long controversy—the most accepted rule being that chloroform always kills 
by paralyzing the heart, while ether is free from that danger. It must be 
confessed that at first sight this view seems to be in accordance with the 
general facts of observation ; but a Jong and careful watching, in which ex- 
periment succeeds experiment, leads in time to this certain truth, that 
chloroform does not always kill by paralyzing the heart, but that with chlo- 
roform, as with ether, the heart will continue to beat after the respiration 
has ceased. The rule, therefore, is not general; the question is how far it 
is at all true. 
To test this, I proceeded first to see whether the heart could be sustained 
in its action while respiration, with an atmosphere containing a narcotizing 
dose of chloroform, was artificially supplied. I found in this experiment no 
difficulty whatever, and no remaining doubt after it. A T-shaped tabe hay- 
ing been inserted into the trachea of a strong animal (a dog) narcotized with 
vapour of chloroform, the animal was made still to breathe air charged with 
the vapour, in steadily increasing dose, until some change occurred. During 
this time, in the deadest silence from all other motions, the sounds of the 
heart were listened to, with the double stethoscope, by myself, while an 
assistant watched for the cessation of respiration. ‘The respiration stops ” 
was the report; but I could still hear, not only the motion of the heart, but 
both the sounds in due order of time. ‘Then the first sound began to fail, 
and soon the second. At this moment, on a signal from me, artificial respi- 
ration, with the same chloroform atmosphere in which the animal had gone 
to sleep, was set up by means of double-acting bellows; and at once, as the 
air filled the lung, the blood made its way again through the heart, the 
motion of the heart returned, the sounds returned, and the general signs of 
life returned. Once more the experiment was tried, and once again with the 
same result; and so decided was the experiment that, on giving it fresh air 
artificially, the animal recovered, in the end, as from simple sleep. 
In a further instance I repeated the famous experiment first performed by 
Hook, with the difference that the animal throughout was held insensible by 
chloroform. In this case, after insensibility was complete, and respiration, 
which for some minutes had been carried on through the tracheal tube, had 
ceased, the heart was directly exposed to view, together with the lungs. The 
heart was pulsating vigorously on both sides, the lungs generally were 
blanched, from the blood ceasing to'make its way by the pulmonary circuit: 
but artificial respiration of the chloroform atmosphere was reestablished ; and 
as the lungs filled with the air the right side of the heart was set at liberty, 
the blood passed over the pulmonary circuit, and on withdrawing the chloro- 
form, and for a brief period supplying the air pure, the general signs of life 
began to reappear. They were, of course, suppressed by repeating the chlo- 
roform ; but before the heart was finally stopped in its action, the fact of being 
_ able to call it again into play by reinducing respiration was several times 
demonstrated. 
Taking a very important practical hint from Dr. M‘Intosh, who read an 
admirable paper at Dundee before this Section, I followed up my research 
by watching the circulation and respiration in young transparent trout 
while they were being subjected to the action of methyl and ethyl com- 
pounds, I was so fortunate at the close of last year as to be able to obtain 
