AFRANIO DO AMARAL 1069 



particular animal which the snake is accustomed to capture has taken place during the 

 phylogenetic evolution of the latter. Venoms are also a complex of many toxic and 

 antigenic principles which have especial tropisms for the different animal tissues. It 

 is not unlikely that these principles which probably have gradually appeared in the 

 venoms are specific weapons to which snakes have had recourse in their struggle for 

 life. This remarkable character of the poison is found especially in such snakes as 

 those which have recourse to only one kind of prey. Among the proteroglyphous, 

 Pelamydrns platuriis (L.) , which feeds on fish, has a venom the M.L.D . of which is as low 

 as 0.00025 gm. for the mudfish, according to Rogers,' and the M.L.D. of the venom of 

 Enhydrina vdakadien Boie, another piscivorous sea snake, is 0.0005 g"^- ^""^ the same 

 fish. The Brazilian "coral-snakes" (especially Micrurus frontalis and M. corallinus), 

 which are all ophiophagous, can kill almost instantaneously any snake, either small or 

 large, poisonous or non-poisonous, such as Pseudoboa cloelia (Daudin), Liophis 

 miliarius (L.), and Crotaliis terrificus. The most striking example of all is that of 

 Bothrops insular is Amaral (solenoglyphous),^ which has become a bird-eater through 

 force of environmental conditions; the M.L.D. of its venom for a pigeon (300 gm.), 

 by intravenous injection, is 0.000004 gm-j while it is 0.000050 for a rabbit (i kg.) 

 also by intravenous injection. 



b) Nature. — Venoms are commonly classified with the proteins on account of their 

 most important reactions and physico-chemical affinities. They lose their toxicity 

 when treated m vitro by such reagents as silver nitrate, sodium and potassium hy- 

 droxide, gold chloride, potassium permanganate, etc. They also become atoxic when 

 treated by heat, but at widely different temperatures which may vary from 65° C. 

 in the case of B. alternata to 120° C. in the case of Lachesis muta, according to Brazil.^ 

 Pancreatic digestion affects the activity of all venoms, making them atoxic; gastric 

 digestion, however, affects only a few, such as those of Crotalus, but not, for instance, 

 those of Vipera, Naja, and Pseudechis. Acids, even in concentrated solution, have 

 different effects, usually destroying only a few of the toxic and antigenic principles 

 of the venom. Glycerin is entirely harmless to venoms, thus serving as their best 

 means of preservation. Some venoms, especially those of Crotalus, change into toxoids 

 by losing their toxophorous group, and perhaps also some of their antigenic principles, 

 when treated by certain chemicals such as calcium hypochlorite, gold chloride, and 

 iodine trichloride. Cold and light have but little effect on the toxicity of dried 

 venoms; electricity and radium, however, gradually destroy them. The venom of 

 Naja is entirely filterable through porcelain candles; that of Pseudechis porpkyriaca 

 consists of two substances, one filterable and neurocytolytic and another non-filter- 

 able and hemocytolytic. Dialysis has a similar effect. The toxic principles of Vipera 

 aspis (L.) venom are undialyzable ; its antigenic principles are dialyzable. Crotalus 

 adamanteus venom loses its hemagglutinin properties but remains hemocytolytic after 

 dialysis. As a rule, the higher the percentage of albuminous material contained in the 

 venom, the more it becomes atoxic by dialysis. Proteroglyphous venoms, which are 



'Rogers, L.: Proc. Roy. Soc, 76, 481 ff. London, 1902. 



". do Amaral, A.: Anex. Mem. Inst. Butantan, i, 44 and 87. 1921. 



3 Brazil, V.: La Defense c. rophidisme, p. 130. 1914. 



