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 eHminated 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 haemorrhagic 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 haemorrhagic 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 100° 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 sunhght. Electricity in a form of high frequency 

 or of constant current reduces the activity of the neurotoxin of the venom. 



