144 VENOMOUS SNAKES AND THE PHENOMENA OF THEIR VENOMS 
conclusively that the rapid death with convulsions following the injection of 
daboia venom is due to the production of extensive intravascular thrombosis. 
C. J. Martin made similar observations with the venom of Pseudechis por- 
phyriacus, but this author showed that pseudechis venom contains at the 
same time a considerable amount of the neurotoxin characteristic of all 
colubrine species. Calmette found that the venoms of Naja produce death 
by attacking first the nuclei of the accessory and hypoglossary nerves and 
then the origin of the pneumogastric nerve in the medulla. The symptoms 
are those of bulbar paralysis. Calmette eliminated from venom its local 
destructive agents by heating and then separating the coagulable proteids of 
the venom. ‘The neurotoxin remains almost unabated in its strength in the 
clear fluid, while the phlogenic principles become inert and are separate from 
the coagulated proteids. Weir Mitchell has shown that crotalus venom 
loses all its hemorrhagic principles by a temperature of about 80° C. without 
losing its neurotoxic properties. Kanthack, Wall, Fraser, Wolfenden, Martin, 
Lamb, Flexner and Noguchi, Noc, and others, all confirmed the thermostabile 
nature of the neurotoxins. 
Besides the high resistance of the neurotoxins to heat, it was also found 
that they retain their toxic properties after a prolonged treatment with alcohol, 
while the hemorrhagic toxins lose all their activity by the same treatment. 
Venom neurotoxins reside in a group of proteins which in their physical 
and chemical reactions fall under the class of albumoses and peptones 
(Mitchell, Reichert, Kanthack, Martin). They are non-precipitable by dialysis 
and brief boiling, and pass through a gelatinized porcelain bougie under the 
pressure of 50 atmospheres (C. J. Martin). The neurotoxic activities of 
these protein constituents are lost on a prolonged boiling, but their protein 
reactions remain unaltered by the boiling. This fact clearly indicates 
that the venom albumoses are not identical with the cleavage products of 
digestion of proteins called albumoses, but differ from the latter in contain- 
ing certain radicals capable of attacking the nervous tissues and showing 
far more lability to the action of high temperature. A complete loss of 
the neurotropic constituents of the venom albumoses can be brought out only 
by heating venom solution to 1oo° C. for an hour or longer. The more con- 
centrated, the slower is the destruction of the venom solution. Heating to 
120° to 135° C. invariably destroys the neurotoxins. According to Calmette 
and Noc, the neurotoxin of the venom of Lachesis lanceolatus is much more 
sensitive to moist heat and is destroyed at 80° C. 
The neurotoxins are not destroyed when the dried native venom is heated 
to 135° C., and they remain also unaltered when subjected to the tempera- 
ture of 191°C. below zero. The rays of the sun seem to have marked 
deteriorating influence upon the neurotoxin when the latter is exposed directly 
in a solution, but not at all in the dried venom. In the presence of fluores- 
cent dyes the neurotoxin in a solution gradually loses its activity when 
directly exposed to the sunlight. Electricity in a form of high frequency 
or of constant current reduces the activity of the neurotoxin of the venom. 
