290 Mr. W. E. Dixon. The Pharmacological _ [Nov. 1, 
the dilatation of vessels. In these experiments the Ringer’s solution at body 
temperature was suddenly changed to one containing 0°01 per cent. of the 
alkaloid, when the outflow from the vein showed a decided increase. It is 
clear, therefore, that one cause of the fall in blood-pressure is vaso-motor. It 
has been suggested, however, by Harvey Gibson from observations on the 
isolated heart of the rabbit that boxwood is a profound cardiac poison. 
His experiments on the isolated heart are easily verified (fig. 2), but of 
course such experiments do not show that, in any possible dosage to a normal 
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Fic. 2.—Record of Isolated Rabbit’s Heart perfused with Oxygenated Ringer’s Solution. 
The top curve shows the effect of injecting 1 cc. of a 0:04-per-cent. solution of the 
alkaloid ; the middle tracing shows the effect of injecting 5 c.c. of the same strength, 
and the bottom curve 10 cc. of a 0°08-per-cent. solution. Time, seconds. Each 
injection was made in 5 seconds. 
animal, the amount present in the blood would be sufficient to exert this 
influence on the action of the heart. Indeed, the amount of boxwood which 
must be administered to an isolated heart in order to produce depression 
also very decidedly influences its nerve supply, to which later reference will 
be made; hearts so treated will be found to have lost their reaction towards 
muscarine and pilocarpine, whilst towards adrenalin their reaction 1s much 
diminished. In order to decide whether boxwood has any cardiac action 
of importance, several experiments were made on the intact heart of: 
anesthetised animals. The results of these experiments showed in each 
