214 C. J. MARTIN. 
observed by Weir Mitchell and Reichert, and Feoktistow, to 
follow the introduction of the venom of Crotalus, Ancistrodon, 
Daboia russellii, and Vipera berus into the circulation. Directly 
the venom reaches the heart there is a sudden great fall of the 
arterial blood pressure. This fall is accompanied by diminution 
in the extent of the accession of pressure due to each beat of the 
heart, and is the more marked the greater the rapidity with which 
the solution of venom is introduced, and the nearer the vein chosen 
for its introduction is to the heart. The extent of this fall is 
dependent on the degree of concentration with which the poison 
reaches the heart. When its dilution with blood is accomplished, 
by introducing it into a vein far removed from the heart, its effect 
~ is lessened, and if the injection be carried out sufficiently slowly, 
this steep descent is absent, and the pressure declines slowly and 
steadily until death. 
Also when the venom is injected into the carotid or vertebral 
artery, so that it is carried away from the heart and well diluted 
with blood before it is returned to this organ, the effect is 
diminished, notwithstanding the fact that under these circum 
stances the poison reaches the nervous system in the greatest : 
concentration. If the fall in pressure is to be ascribed (a8 
Mitchell and Reichert concluded was the case in their exper 
ments) to the sudden relaxation of the arterioles in the abdominal 
area, by paralysis of the vaso-motor centre in the medulla, one 
would expect to obtain the most marked result when the poison 
was enabled to operate upon the medulla in greatest concentration 
and not the reverse result, as I have always obtained. . 
The initial fall of pressure may be only temporary, ean 
course of a few minutes to one hour may rise again to nearly 
normal, as is shown in the majority of the experiments. 
This recovery, when it occurs, does not however last long if 
fatal dose has been injected. After remaining as high, OF pe 
as high as before the injection, for a period varying from 4 ug 
minutes to some hours, according to the dose whi | 
