76 THOMPSON YATES AND JOHNSTON LABORATORIES REPORT 
VJI. 38 mgrms. CHC1 3 per Litre Modified Ringer's Solution 
(CJ/C/j in -0038 per cent, dilution} 
Under perfusion of this strength of CHC1 ? solution through the coronary 
system the beat of the auricle suffered a reduction varying from 30 per cent, to 
75 per cent, in five observations. The mean value of the reduction was 55 per 
cent. This estimate does not include the observations in Heart 19, an irregularly 
beating heart, in which the weakening by the solution amounted to certainly more 
than 70 per cent. In none of the hearts used was the auricular beat ever 
extinguished even temporarily by this solution. 
The average weakening of the ventricular beat was 96 per cent., and it 
was usually extinguished altogether (temporarily). 
Recovery was invariably rapid and complete, both in auricle and ventricle. 
Even when the perfusion of the CHC1 3 was continuously maintained for ten minutes 
the recovery on its discontinuance was prompt and complete. The heart thirty 
seconds after the discontinuance was beating as well as prior to the chloroformization. 
When the exhibition of the drug in this strength of solution was prolonged 
it was noticed that the ventricle beat improved somewhat in the latter part of the 
administration upon what it was during the first few minutes of the perfusion ; for 
instance, it would be visibly beating in the tenth minute, although without visible 
beat in the third minute. 
VIII. 30 mgrms. CHClj per Litre Modified Ringer's Solution 
(CHCL in '003 per cent, dilution) 
Under perfusion of its coronary system, with this strength CHC1 3 solution, 
the mammalian heart showed a weakening of the auricular beat, as measured by 
amount of reduction of excursion of the recording lever, varying from 45 per cent. 
(Heart 29) to 85 per cent. (Heart 30). In one and the same heart it varied con- 
siderably, thus, from 28 per cent, at outset in Heart 28 to 62 per cent, later during 
the experiment. The reduction of amplitude of beat in twenty-one observations on 
five hearts averaged 66 - 8 per cent. The weakening did not occur so rapidly in the 
auricle as in the ventricle. 
The degree of impairment of the ventricle's beat varied even more than that 
of the auricle, i.e., from 15 per cent, to 95 per cent. The mean reduction in 
nineteen observations on the ventricles of four hearts was 91*7 per cent. The 
amount of reduction did not vary so widely in successive observations on the same 
individual heart as for observations on different hearts. The beat of the ventricle 
was in four observations (Heart 8) extinguished (temporarily) by this strength of 
CHC1 ? solution. 
The duration of the dose with this solution was varied from forty-five 
seconds up to ten minutes. Sometimes weakening of the ventricle beat became 
