PON ee le REE ee eee NT eee Pe Ee aN Tp ae 
PHYSIOLOGICAL ACTION OF VENOM OF BLACK SNAKE. 271 
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the alteration of the vessel wall, the coagulability of the blood is 
greatly diminished, or altogether in abeyance, so that the blood 
which escapes clots slowly, or not at all. In addition, the veins 
in some areas are often thrombosed, thus raising the pressure in 
the capillaries of that area, and so increasing the extravasation. 
I have elsewhere mentioned that when dogs are the animals 
experimented with, the blood in the portal vein is particularly 
liable to be coagulated by the action of the poison. When this 
has happened the whole of the alimentary track is the situation 
of extensive hemorhages, and during life the animal passes blood 
by the rectum, and vomits blood-stained fluid. When the portal 
vein has not been thrombosed, the alimentary tract does not suffer 
more than the rest of the organs. 
Unless the poison be injected subcutaneously in large amount, 
or else introduced directly into the circulation, the extravasation 
of blood into the organs does not play a very important réle in 
poisoning by Pseudechis venom. There is however one organ 
which has, in my experiments with mammals never escaped, viz., 
the lungs. These have invariably been the seat of hemorrhages 
of greater or less extent. Sometimes a considerable portion of one 
or both lungs has been found more or less solid from extravasated 
lood. Microscopical examination of a hemorrhagic Jung of an 
animal which has succumbed in a few hours from the injection of 
the poison, shows portions of the organ infiltrated with blood. 
The alveoli, interalveolar tissues, and small bronchi appear one 
mass of blood corpuscles. A similarly affected lung from an 
animal which had survived two or three days, shows patches of 
lung, in which the tissues are barely recognisable, and are 
imbedded in a mass of fibrin, and more or less altered blood 
Pigment. These necrosed areas are surrounded by a ring of small 
celled infiltration separating it from the healthy lung around. 
; It is quite possible that some of the hemorrhagic extravasation 
to the lungs is associated with thrombosis in the smaller branches 
of the pulmonary artery. 
