236 VENOMOUS SNAKES AND THE PHENOMENA OF THEIR VENOMS 
which every trace of hemolysin had been removed by Kyes’s method for the 
isolation of venom lecithid. It was found that this modified venom solution 
was highly toxic, especially upon the nervous system. In various pharma- 
cological tests it was identical with the raw venom as far as its lethal prop- 
erties are concerned. Thus it was chiefly the neurotoxin which was contained 
in that hemolysin-free solution of cobra venom which was hence called the 
neurotoxin. Jacoby! found, however, a very important difference between 
the neurotoxin and the raw cobra venom, when he attempted to neutralize 
the former with Calmette’s antivenin. The antivenin was protective against 
the raw venom, but not at all against the isolated neurotoxin. This incapa- 
bility of Calmette’s antivenin to neutralize the neurotoxin was ascribed to a 
possible modification of the molecule during the isolation from hemolysin, 
and a parallel was drawn between this and that observed by Kyes with the 
isolated cobra lecithid. On the other hand, Jacoby succeeded in producing 
immunity in rabbits against the isolated neurotoxin and found that the 
serum of the immunized animals had neutralizing properties for the neuro- 
toxin as well as the raw cobra venom. ‘This singular phenomenon was also 
observed by Kyes with his hemolytic lecithid. 
SPECIFICITY OF ANTIVENINS DUE TO DIFFERENCES IN INDIVIDUAL 
CYTOTROPIC TOXINS OF VENOMS OF DIFFERENT SPECIES. 
In the past few years the question of venom immunity has become rather 
far-reaching. Since the establishment of the facts that the action of anti- 
venin is specific and that an antivenin may be incapable of neutralizing one 
set of toxins, while the other set may be completely counteracted, attention 
has been given to whether or not one particular toxin is common to the venoms 
of different species. We have already seen that all venoms of Elapinz and 
Hydrophiine contain one type toxin destructive to the nervous system. Is 
the neurotoxin contained in the venom of Naja tripudians identical with that 
present in Bungarus or Enhydrina? The venoms of vipers and of certain 
Australian Colubrine are known to contain fibrin ferment, but is the fibrin 
ferment of the venom of Daboia identical with that of Echis or Pseudechis or 
Notechis? ‘The crotaline venoms contain a considerable amount of hemor- 
rhagin, but is that principle contained in Crotalus identical with that of An- 
cistrodon? The same inquiry arises also as to the hemolysin and other 
cytotoxins contained in different kinds of venoms. 
This question of the specificity of various individual type toxins is of the 
utmost importance both from practical and theoretical standpoints. ‘To 
those familiar with the almost fabulous discriminative immunity reactions 
of living organisms to a countless variety of toxins and albuminoid bodies, 
it may not appear extraordinary that the neurotoxins, hemolysins, fibrin 
ferments, hemorrhagins, and still other cytotoxins of the venom of one species 
should differ from the similar principles of other species of snakes. Never- 
1 Jacoby. Ueber die Wirkung des Kobragiftes auf das Nervensystem. Beitr. z. wissensch. Medicin 
und Chemie. Festschrift zu Ehren des 60. Geburtstages von Ernst Salowski. Berlin, 1904, 200. 
