CHAPTER XVII. 

 CYTOLYSINS IN SNAKE VENOM. 



The death-dealing neurotoxins and the haemorrhagins are most important 

 of all cytolysins contained in snake venom, and the best-studied are the hsemo- 

 lysins, including the erythrocytolysins and leucocytolysins. Full descriptions 

 of these three groups of cytolysins have already been given elsewhere under 

 separate headings and I shall not repeat them in the present section. 



Apart from the neurolysins, haemorrhagins, and haemolysins several other 

 cytolysins have been demonstrated in snake venom by Flexner and Noguchi,^ 

 and somewhat later by Calmette and Noc.^ 



The results of experiments obtained by Flexner and Noguchi are given in 

 table 13. The venoms employed were those of Cobra, Ancistrodon piscivorus, 

 Crotalus adamanleus, Daboia russellii, and Lachesis jiavoviridis. 



The animal cells came from a wide range of animals, including warm- 

 blooded and cold-blooded species. The former, limited to certain species 

 of mammalia, had served for the study of the effects of venom upon the cells 

 of the liver, kidney, and testes; the latter for that upon the spermatozoa, ova, 

 and nerve cells. The cells were obtained by preparing emulsions of the solid 

 organs and by suspending the expressed spermatozoa or separated ova in 

 appropriate fluids. In the case of warm-blooded animals 0.85 per cent 

 sahne solution, and in the case of the marine animals fresh sea-water, were 

 employed. The strength of the emulsions of the cells was approximately 

 5 per cent of the organs used. 



The venom was dissolved in 0.85 per cent saline solution or in sea-water. 



The temperature to which mixtures of emulsion and venom were exposed 

 were those of the room or thermostat (37° C), depending, usually, on the 

 origin of the cells. Observations of the effects were made (i) in test-tubes 

 with the naked eye and (2) by means of microscopical examination. 



EFFECT OF VENOM ON CELLS OF WARM-BLOODED ANIMALS.^ 

 The animals used in these experiments were dog, guinea-pig, rabbit, rat, 

 and sheep. The venoms employed were daboia and crotalus. The experi- 

 ments given would seem to prove conclusively that venom contains solvents 

 for the parenchymatous cells of several animals, and that considerable dif- 

 ferences in activity in this respect occur, according to the source of the venom. 

 Flexner and Noguchi have also tested other venoms, for example, from the 

 cobra, water-moccasin, and habu, and have found them to possess similar 

 cytolytic properties; but their experiments show that daboia venom contains 

 the most and crotalus venom the least active solvents, the other venoms 

 arranging themselves in the order: water-moccasin, cobra. (Table 13.) 



» Flexner and Noguchi. On the plurality of cytolysins in snake venom. 



* Noc. Sur quelques propriet6s physiologiques de differents venins de serpents. Ann. Inst. Pasteur, 



1904, XVIII, 387. 

 3 Rabbits' spermatozoa are seen to stop their motion under the influence of crotalus venom. (Weir 



MitcheU and Reichert.) 



199 



