D.—Various Diastasic Actions of Venoms.
So long ago as 1884, de Lacerda, in his “Leçons sur le venin des serpents du Brésil,” described the results of his researches upon the diastasic actions of venom. He proved that venom emulsifies fats, causes milk to curdle, and does not saccharise starch. But the solutions of venom employed by this author were not sterile, so that putrefactive phenomena may be believed to have occurred in the course of his experiments.
The subject has been studied afresh by Wehrmann[60] in my laboratory, and afterwards by Lannoy.[61] These two investigators have shown that venoms do not hydrolyse either starch or inulin. Cobra-venom and that of Vipera change saccharose very slightly. They do not modify the glucosides (amygdalin, coniferin, salicin, arbutin, and digitalin); they therefore do not contain emulsin.
On the other hand, these venoms possess, as I have already stated, very interesting kinasic properties, which have been pointed out by Delezenne.[62] They consist in the fact that while venom alone is incapable of digesting cooked albumin, we have only to add to a pancreatic juice, in itself devoid of effect upon albumin, a trace of venom, to see this albumin immediately become digested.
Lachesis-venom is especially active in this respect. In Delezenne’s experiments it was generally sufficient to add to 1 c.c. of inactive pancreatic juice, 0·5 to 1 c.c. of a 1 in 1,000 solution, that is 0·5 to 1 milligramme of venom, to obtain the digestion of a cube of albumin weighing 0·5 gramme in the space of from ten to twelve hours. Much weaker doses, ⅕, ⅒, sometimes even 1/80 of a milligramme still gave the same result, with this sole difference that digestion took twenty-four, forty-eight, and even seventy-two hours to become complete.
Cobra-venom was found to be a little less active than the foregoing, but still its action was usually evident enough when it was employed in a dose of 0·5 milligramme or even 0·1 milligramme. As for the venom of Vipera berus, it was often necessary to employ it in doses from five to ten times stronger in order to obtain the same result.
Delezenne has ascertained, on the other hand, that these venoms entirely lose their kinasic power when they are subjected to ebullition for fifteen minutes.
This kinase or diastase, capable of quickening the inert pancreatic juice, must evidently be of very great utility to the reptile in enabling it to digest its prey. Venom, therefore, is not, as has long been believed, a purely defensive secretion; it corresponds to a physiological necessity, like that of the intestinal or pancreatic juice. Herein is to be found the explanation of the fact that the non-poisonous snakes, although destitute of organs of inoculation, possess supralabial or parotid glands which produce venomous saliva.
Experiments have been made by Ch. Féré[63] to determine the effect upon the development of the embryo of the introduction of venom into the albumen of the egg of the fowl. He found that 83 per cent. of the embryos, developed in eggs intoxicated with 0·05 milligramme of viper-venom and opened after being incubated for seventy-two hours, exhibited various anomalies in development.