8o THOMPSON YATES AND JOHNSTON LABORATORIES REPORT 
When the beat had been reduced by the CHC1 3 solution to extinction, to observe any- 
inhibitory effect, of course, became impossible, but on faradizing the cardiac nerve 
striking augmento-accelerator effects were often observed. In some cases the heart, 
when it had been rendered flaccid and motionless by the CHC1 5 perfusion, was, by a 
brief faradization of the cardiac nerve, at once thrown into vigorous action, and 
remained so lor a couple of minutes or so, in spite of continued administration of 
the CHC1 3 solution all the time. Fig. 12 illustrates this. CHC1, in -002 per cent, 
had been already administered to the heart lor ninety-five seconds, and the beat of the 
ventricle had entirely ceased from the first minute, when cardiae nerve was stimulated 
for fifteen seconds. In seven seconds from commencement of the stimulation the 
ventricle, although there was no remission of the CHC1 ? administration, recommenced 
beating. It soon attained an extraordinary force and frequency. It continued to 
beat for about 100 seconds, giving a series of 196 beats, in spite of the unremitted 
continued perfusion with the CHC1 ; solution. 
Influence of Duration of Exhibition of the CHC1 3 Solution 
A notable feature of the action of CHC1 ; in dilute solution on the isolated 
mammalian heart is absence of all cumulative aggravation. The solution produces 
its full effect in a comparatively few seconds, e.g., seventy seconds after reaching the 
coronary system. Further prolongation of the administration does not render the 
depression more profound, but merely maintains it. On the discontinuance of the 
administration the effect passes off at once, in almost as few seconds as it took for 
its establishment. 
With strong CHC1 ; solutions the duration of the administration does, no doubt, 
aggravate the depression of vitality. Thus with one per thousand CHC1 5 solution 
the heart that is not killed by perfusion for thirty seconds is killed by perfusion for 
sixty seconds. But these strong solutions do not come within the scope of thera- 
peutic enquiry. Of moderate and weak solutions it may be confidently asserted that 
on the isolated mammalian heart their influence is marked by absence of cumulative 
effect. In some of our observations we have kept the chloroform solution, even in 
the strength of 150 mgrms. per litre of the Ringer's solution (i.e., CHC1; in -015 
per cent, dilution) flowing continuously through the blood-vessels of the heart for 
twenty minutes at a time. Even over such periods as these no cumulative effect has 
been obvious ; indeed, the depression of the heart's beat has been slightly less at the 
end than at the outset of that time (-.ee following paragraph), and on replacing the 
chloroform solution by the pure Ringer's solution the recovery of the cardiac activity 
to its full previous degree has occurred absolutely promptly. For instance, in 
fifty seconds after replacement of the chloroform solution by the unchloroformed 
solution the heart has been beating as vigorously as it had been prior to the exhibition 
of the drug, and in spite of its forced abeyance for twenty minutes under the action 
of the drug. 
