PHYSIOLOGICAL ACTION OF VENOM OF BLACK SNAKE. 173 
often for a minute or more after the circulation is at a standstill. 
If records of the arterial blood pressure and of the respiratory 
movements be taken in these experiments, the moment of clotting 
in the arteries is indicated on the tracing, by the disappearance 
of heart-beats, and the straight line described by the style some 
distance above the abscissa. I have in my possession a number 
of tracings showing the continuance of respiration for periods up to 
two minutes after the circulation must have been completely 
blocked. 
These experiments show that as long as the blood will flow 
through the pulmonary artery and its branches, there is nothing 
to prevent its normal gaseous interchange, as far as the respiratory 
movements are concerned. That it takes up oxygen as usual is 
seen by the colour of the blood in the left heart. 
To ascertain whether the modification of the coagulability of 
the blood during its passage through the lungs depended on its 
altered gaseous condition, I followed the method which Wright 
used, to determine the cause of the distribution of thrombosis 
after injections of Wooldridge’s tissue fibrinogen. This observer 
rendered animals dyspneeic by compression of the trachea previous 
to the injection of doses, which, as he had determined would, 
without this treatment, only give rise to a very limited intra- 
Vascular clotting. The results of injecting “tissue-fibrinogen sg 
into the circulation when in this venous condition were strikingly 
altered. My experiments were performed on rabbits of like 
weight. Several were intravenously injected, under exactly 
similar circumstances, with gradually decreasing doses of venom, 
until a dose was found which produced a very limited clotting or 
hone at all. Other rabbits of the same weight were then rendered 
dyspneic by compression of the trachea continued for one minute 
before the subminimal dose of venom was introduced. These 
Subminimal doses produced in every case complete clotting 
throughout the whole vascular system. 
1 e 
Journal of Physiology, Vol. x1t., No. 2. 
