DOSAGE OF THE MAMMALIAN HEART BY CHLOROFORM 
73 
I. 1,500 mgrms. CHClj per Litre of Modified Ringer's Solution 
(CHCl^ in "15 per cent, dilution) 
This solution administered for thirty seconds abolished, in less than twenty 
seconds, the beat both of auricle and ventricle. But, on replacing the chloroform solution 
by pure s.dine, the beat was subsequently completely recovered in both, in auricle 
slightly earlier than in ventricle. The ventricle recommenced beating about seventy- 
eight seconds after the CHC1 ; mixture had been discontinued ; its recovery was abrupt in 
the sense that its very first beat was of considerable extent and power. The recovery 
of the auricular beat began more gradually. 
Permanent abolition of the beat of the ventricle resulted from perfusion of 
this solution for sixty seconds ; fibrillar contractions of the ventricle were all that 
subsequently were obtainable. But the auricle recommenced beating regularly 
seventy-five seconds after the end of the one minute's CHC1 3 perfusion, and was of 
normal extent and vigour 125 seconds later. 
The resistance of the auricle-muscle to CHC1 3 in these high percentages 
appears much greater than is that of the ventricular. Perfusion with this - ooi solution 
for even sixty seconds, although completely and permanently annulling the ventricular 
beat, makes no permanent impression upon that of the auricle. The auricle began to 
show recovery about seventy-five seconds after cessation of the administrations of this 
CHCi 3 solution, whether the solution had been perfusing it for one, two, three, or 
five minutes, respectively. 
II. 750 mgrms. CHC1, per Litre Modified Ringer's Solution 
(CHCl^ in -075 per cent, dilution') 
This strength of solution almost immediately (in less than thirty seconds) 
extinguished the beat of both auricle and ventricle. As to subsequent recovery, in 
one heart both auricle and ventricle recovered completely subsequent to a continuous 
administration of the solution for five minutes ; but the ventricle of the same heart 
completely succumbed to continuous administration of the solution for nine minutes, 
only fibrillar twitchings appearing in it subsequently. In another heart, administra- 
tion of the same strength of solution for 305 seconds (Fig. 2) permanently 
destroyed the ventricular beat. In a third heart, the same strength of solution 
stopped the ventricular beat irrecoverably by one minute's perfusion, fibrillar twitchings 
being all that could be subsequently obtained. 
In all these three hearts the auricle showed itself much more able to recover 
from CHCh than did the ventricle. Even after nine minutes' perfusion with the 
solution the auricle recovered, although, to do so, it requires an interval of more 
than fifteen minutes' perfusion with the oxygented Ringer's solution. 
With shorter periods of administration of the CHC1 3 solution, the auricle had 
usually been beating for fifty seconds to sixty seconds before the ventricle recommenced. 
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