THE ACTION OF SNAKE VENOM UPON COLD-BLOODED ANIMALS 271 



THE ACTION OF SNAKE VENOM UPON COLD-BLOODED ANIMALS. 



Since the writings of Fontana, Weir Mitchell alone seems to have concerned 

 himself with the study of the action of snake venom upon cold-blooded animals. 

 Having studied and described the action of rattlesnake venom upon frogs and upon 

 Crotalus itself, he intended, as appears from a paragraph in his earlier paper on 

 venom, to extend his observations to a wider class of animals. Thus he writes: 



"It was my intention to examine, in the next place, the effects of the venom upon leeches, 

 fish, eels, and crustacean animals, but for some reasons, which it is needless to relate, I was 

 obliged to postpone these observations until some future occasion." 1 



The following orders of animals were tested against venom: Reptilia, Amphibia, 

 Pisces, Insecta, Crustacea, Vermes, Mollusca, Echinodermata. 



Several kinds of venom were employed: cobra, water-moccasin, and rattlesnake. 

 All had been previously dried, and hence they were dissolved, before injection, in 

 sterile sea-water or normal saline solution, according as they were to be introduced 

 into fresh or salt water animals. The mode of injection varied with the animal 

 species employed: in higher forms the peritoneum was selected, in lower forms the 

 body cavities or water vascular system. Some of the vermes gave unsatisfactory 

 results in respect to the dosage because of strong muscular contraction produced by 

 the needle puncture and the presence of septa throughout the body. It was almost 

 impossible to calculate the exact amount of venom introduced into these animals. 



Each experiment was accompanied by at least two control animals maintained 

 under precisely the same external conditions. In every case in which the cause of 

 death was doubtful the experiment was repeated. In general, it may be stated 

 that the animals used in the experiments stood the necessary handling and cap- 

 tivity without serious drawbacks. But in a few instances the degree of sensitive- 

 ness to these procedures was found to be very great. Thus, in the case of several 

 kinds of small fish, e.g., pollack, silver-side, pipe-fish, this sensitiveness was so 

 great that they did not survive beyond 24 hours in captivity. Animals surviving 

 the injections were, as a rule, killed at the end of the experiment and examined 

 for local and general lesions. 



The results of the study are given in tabulated form. In reviewing the tables, 

 one is impressed with the wide degree of susceptibility to snake venom exhibited 

 by cold-blooded animals. On analyzing the effects produced, it becomes quickly 

 evident that cobra venom exerts little if any local action, although it is the most 

 toxic of all venoms employed. Crotalus venom, on the other hand, while exhibit- 

 ing the least general toxicity, displays the greatest local action. Water-moccasin 

 venom occupies an intermediate position in this regard. 



The chief local effect produced by rattlesnake and water-moccasin venoms is 

 the escape of red blood corpuscles from the vessel; only rarely is macroscopic necro- 

 sis of tissue visible. This production of haemorrhage is, however, not restricted 

 to the site of injection of the venom, but in some animals generalized haemorrhages 

 also take place. This latter effect was noticed chiefly in fishes, from which the blood 

 may escape in such large quantity from the gills as to color the sea-water. In 

 other instances, haemorrhages into the skin occur, and I have noticed during life, 

 in the dog-fish poisoned by crotalus venom, the occurrence of intracranial haemor- 

 rhage. Only one species of fish — the puffer — was wholly insusceptible to the locally 

 irritating principles of venom; it succumbed, however, to the general toxic effects 

 of all the venoms. 



It would appear as if the chief toxic effects of crotalus and moccasin venoms 

 are the outcome of their local action, and yet the general toxic constituents which 



1 Researches upon the venom of rattlesnake, with an investigation on the anatomy and physiology 

 of the organs concerned. Smithsonian Miscellaneous Collections, vol. XII, Washington, 1861. 



