DOSAGE OF THE MAMMALIAN HEART BY CHLOROFORM 
The amplitude of the heart's beat has in these perfusions been as a fact somewhat less 
reduced than with corresponding dosage exhibited in 'Ringer.' The results are 
given in Table XIII. 
Influence of Temperature 
We have been careful to note the temperature of the fluid entering the 
coronary system. We have performed control observations on the effect on the 
beating of the heart of gradual and of more sudden variations of temperature in the 
fluid supplied to the heart. As to the former, the exhaustive enquiries by Newell 
Martin (6 and 2) and by Langendorff (7) stand. So definite a quickening of the 
cardiac rhythm follows pari persen, with gradual raising of its temperature, that 
Newell Martin formulated a numerical law correlating the two. Langendorff in 
result of his own researches modifies Newell Martin's ratio. 
Our observations on the effect of CHC1, solutions on the heart were con- 
ducted between 34 0 C. and 38°C. We find from our control experiments that the 
slight variations in temperature occurring in our individual CHC1 3 experiments do not 
confuse the issues raised and studied in those experiments. 
It is the slight rapid changes that have required guarding against by us, 
namely, when one or other solution was first turned on. This source of error is 
avoided by the 3-way taps. The tap has been turned so as to discharge by the side 
path any fluid that has lain in the short tubing outside the water bath (though jacketed 
in cotton wool). Our aortic thermometer has shown us that by this means we have 
usually avoided even slight alterations of temperature. The readings of the 
thermometer have been always recorded. Such control experiments as we have made 
on this point show that the influence of the more sudden slight changes is of the 
same order as the considerably more gradual changes which we have also made 
observations upon, the effects of which were recorded by Newell Martin and 
Langdendorff. In our fuller report we shall furnish further evidence to this 
effect. 
Excitation of the Cardiac Nerves 
The cardiac nerves, lying in front of the root of the lung, were faradized ? 
and their effect on the isolated heart recorded on many occasions. Typical vago- 
inhibitory effects on the auricle, and also on the ventricle, were almost uniformly 
obtained. The inhibitory effect was more marked on auricle than on ventricle. 
(Fig. 11). It was usually succeeded by very marked augmento-accelerator action, last- 
ing many seconds, or even some minutes. 
Chloroformization does not easily abolish these effects of stimulation. When 
the contractions were deeply reduced, almost to extinction, by the CHC1, perfusion, 
stimulation of the cardiac nerve would still cause slowing frequency-rate or diastolic 
standstill ; this was followed often by marked augmentation or acceleration, or both. 
