20 
blooded animals. This reaction is entirely qiialitatire and, aside 
from differences due to variation in the action of the vagi, is always 
very uniform. In estimating the effects of a drug upon the human 
heart, however, it is preferable to experiment upon warm-blooded 
animals, and to choose those in which the vagus action is weU devel- 
oped. In this way the experimental data may be said to represent 
not only the qualitative but also quite closely the quantitative 
effects in man. Therefore, to check the residts obtained by per- 
fusing the frog's heart with acetanihde and with mixtiues of acet- 
anilide and other drugs, a series of experiments were carried out, 
using dogs as experimental animals. These animals were anaesthe- 
tized by giviug hypodermic injections of morphine sulphate, 0.010 
gram per kilogram body weight, and this was followed in the coiuse 
of a half hour to an hoiu by chloretone, O.ISO gram per kilogram 
dissolved in a small amoimt of alcohol (1 gram chloretone to 2 c. c. 95 
per cent alcohol), which, after dilution with a small amount of water, 
was introduced into the stomach by means of a stomach tube. Fol- 
lowing the appearance of complete anesthesia a tracheal cannula was 
introduced to provide for artiffcial respiration, the air being properly 
warmed by passing it through a cod submerged in hot water. The 
heart was then exposed by a median incision reaching to the dia- 
phragm, the pericardial sac removed, and the ventricle attached to a 
modified form of the Roy-Adami myocardiograph. Blood pressiue 
tracings from the carotid were also taken, using the ordinary mer- 
ciuy manometer to record the changes in pressiue produced by the 
drug, Canmdse were placed in both the right and left saphenous 
veins — one for the injection of the acetardlide.the other for the injec- 
tion of the caffeine citrate or sodium bicarbonate^ which was used 
to determine if there were any antagonism between these drugs and 
acetanihde. 
Acetanilide is so slightly soluble in physiological salt solution that 
it was necessary to inject it as an emulsion. This was formed with 
mucilage of acacia, the amoimt used being as small as possible, and 
then chluted with salt solution. To insiue uniformity of dosage i 
the emulsion was thoroughly shaken before each injection, since the j 
suspension of the acetanilide was only temporary. 
Injections of small amoimts (0.200 to 0.600 gram) of acetanilide 
was usually fohowed by a momentary increase in the strength of the ! 
heart, the systohc phase being more complete and the relaxation 
only shghtly lessened. This effect lasted for a few seconds only and j" 
was succeeded by a rapid and marked decrease in efficiency, the 
contractions growing cpiickly less complete, while the relaxations 
were scarcely affected at aU. In some instances the amplitude 
(efficiency (?)) was slightly greater after recovery from or as a late 
effect of the drug. As in the case of the perfusion experiments it 
