PHYSIOLOGICAL ACTION OF VENOM OF BLACK SNAKE. 245 
It is not, however, so easy to eliminate the influence of deficient 
circulation, as a possible cause of the symptoms of general paralysis 
of the cord which occur in poisoned animals, because the rest of 
the nervous system does not exhibit the same degree of sensitiveness 
as the respiratory centre. Nevertheless, one may infer that a 
poison which produces so deadly a paralysing effect upon a special 
group of nerve cells, will exert the same influence though in lesser 
degree upon the rest of the nervous system. ‘There is indeed 
absolute evidence of this, in the case of cold-blooded vertebrates, 
such as frogs, and although with mammals the evidence is not so 
completely satisfactory, it nevertheless leaves no reasonable doubt 
that a diminution of the reflex activity of the cord, due to the 
direct action of this venom on the nerve cells, exists after the 
injection of the poison. 
In the section devoted to the consideration of the effect of the 
poison on the circulation, I stated that after the introduction of 
venom into a vein, a great fall of blood pressure occurred, which 
was accounted for by a direct paralysing effect of the poison upon 
the heart. When, however the quantity injected was a small one, 
the blood pressure very soon regained its former height, and the 
circulation was as well maintained as previously. Nevertheless 
the condition of the nervous system of the animal is very different 
to that immediately preceding the injection. When removed 
from the table it shows great weakness, and is often unable to 
walk, or even to stand, but lies helplessly in any position in which 
it may have fallen after a few incoordinate attempts to regain 
4 normal attitude. Its tendon reflexes are feeble or altogether 
aesent, and it reacts sluggishly to any form of cutaneous 
stimulation, 
Rabbits of about two kilogrammes in weight, which have 
received “01 gramme of venom subcutaneously, die in from two to 
three hours. The immediate cause of death, as I shall presently 
om, is due in most cases to respiratory failure. If, directly the 
respiration becomes shallow, artificial inflation of the lungs be 
employed, they live some fifteen or twenty minutes longer. In 
