PHYSICAL AND CHEMICAL PROPERTIES OF SNAKE VENOM 79 
CHEMICAL NATURE OF SNAKE VENOM. 
The venom of snakes is a secretion of a serous (namely, albuminous) gland, 
which resembles in its phylogeny the parotid of the mammalian class, and is 
composed of proteins, carbohydrates, salts, water, and certain occasional 
admixtures of abrased epithelial cells or saprophytic micro-organisms. The 
percentage of proteid substances, which are the main components of the 
venom, is between 75 to 50 per cent, although there are certain proportionate 
fluctuations according to different individuals or species. The amount of 
fats and mucin is not very large, leaving the remaining percentage to water. 
The salts found in venom are chlorides and phosphates of calcium, mag- 
nesium, and ammonium, and are present only in small quantities. 
Our knowledge concerning the chemical nature of venom has passed 
through many phases of evolution and is constantly moving forward. I shall 
here attempt to give a brief résumé of the investigations which supply the 
principal facts upon which our chemical knowledge is based, as well as those 
which once served to promote our knowledge. 
Lucien Bonaparte (1843) demonstrated that the most active principle of 
Vipera berus is a protein resembling digestive ferments, and designated it 
viperine or echidnine.1 
S. Weir Mitchell and Reichert (1886) made very exhaustive studies upon 
the venom of poisonous serpents, in which the chemical side of the problem 
was also ably handled. 
According to their analysis there are in venom at least two distinct classes 
of proteins —one including the globulins and the other the peptones. In 
distinguishing these two kinds of proteins they refer to the facts that after a 
thorough dialysis there appears in the dialyzer a large amount of whitish pre- 
cipitate, which, after being separated from the fluid portion of the venom 
by means of filtration, is found to belong to the globulin group. The filtrate 
contains some proteins in solution, as it gave a proteid reaction. This latter 
protein is found to produce no coagulation by brief boiling; not precipitable 
by weak or strong mineral acids, or by solutions of ferri-chlorides or cupric 
sulphate; precipitated, but not coagulated, by absolute alcohol;? and if placed 
in a dialyzer it is found to be readily dialyzable. Thus, from these general 
reactions this was placed among the peptones. 
As will soon be detailed in tabulated form, the globulins which separated 
from the venom solution by dialysis are again differentiated into three varie- 
ties, all of which agree, however, in general properties in that they are insoluble 
in distilled water, soluble in weak neutral saline solution, and soluble in 
dilute acids and alkalies. They become turbid at about 60° C. and are 
fully coagulated at a point a little above 70° C. 
The ways of preparing these three globulins are given below. For this 


1 He precipitated the proteins of the viper’s venom with alcohol and found that the precipitate is poison- 
ous when redissolved in water. This differs from Mitchell’s method for preparation of crotaline, 
as the latter was precipitated not from the filtrate of the boiled venom but from the fresh fluid. 
2 No effect upon the cobra peptone. 
