VENOM OF THE AUSTRALIAN BLACK SNAKE. 151 
the poison reaches the blood, and I think I am now in a position 
to completely elucidate the matter. 
With this object it is necessary to consider for a moment the 
chemical constitution of snake venoms. Venoms are solutions of 
proteids, together with a trace of inorganic salts and a small 
quantity of an organic acid and colouring matter. All venoms 
so far investigated contain at least two kinds of proteids, one of 
which is precipitated by heating the solution. The relative 
amounts of these two proteids are not constant in venoms from 
different species of snakes. Weir Mitchell and Reichert! found 
that the proportion of coagulable to total proteid in the poisons 
of these different kinds of snake was— 
Crotalus ae 
Ancistrodon ... 87% 
Cobra... nan AO hy 
The physiological action of these three venoms varies very 
greatly, and in the same order as their content of coagulable proteid. 
Crotalus venom produces the greatest destruction of cells generally, 
@.g., blood corpuscles, epithelium of vessels, and epithelium of 
kidney. Ancistrodon venom operates on these elements less than 
Crotalus poison but much more than that of Cobra. The poison of 
the Cobra exercises comparatively little effect on tissues generally, 
but confines its action principally to nerve cells, and those nerve 
cells constituting the respiratory centre in particular. A further 
interesting observation by these authors, is, that after heating, 
Crotalus or Ancistrodon venom to 80° C., by which means the 
coagulable proteid is separated in an insoluble form, these venoms 
no longer produce their destructive effect on blood and tissues, 
but now kill by paralysis of the respiratory centre, as is the case 
with Cobra posion, 
Peeudechis poison when injected into dogs, produces wholesale 
destruction of blood corpuscles the products of their destruction 
“ausing thrombosis. When however, this venom is previously 
1 Smithsonian Contributions to Knowledge, Vol. xxvi. 
° ; : 
