144 PHYTOTOXINS AND ZOOTOXINS 



stance which seems to be a polymer of the ophiotoxin, (C34H54O21). 

 Possibly these glucosides are bound to proteins, forming compound 

 proteins which act as specific antigens. According to this work the 

 snake venoms and the dermal poisons of toads and frogs are all closely 

 related substances. 



Enzymes in Venoms. — .\s venom causes rapid liquefaction of tissues into 

 which it is injected, Ploxner and Noguchi^" tested crotalus and cobra venom for 

 proteases, and found that the\^ digested muscle rapidlj', and also gelatin and 

 unboiled fibrin; whereas boiled fibiin and boiled egg-albumen were undigested.^' 

 Kinases and nucleases are also present in venoms (Delezenne).*- \\'ehrmann'^ 

 found that venom digests fibrin and inverts saccharose, but does not digest starch. 

 Martin^^ found fibrin ferments in various venoms, which are probably important 

 agents in causing thrombosis. There are also active lipases in venom=, to which 

 many of the effects, especially hemolj'sis and fatty degeneration of the tissues, 

 may be at least partly due (Noguchi), and the hemolysin of cobia venom seems to 

 be a lipase that splits lecithin into hemolytic substances (Coca).^* Delezenne'- 

 found zinc always present in venom and attributes to it a relation to the enzyme 

 activity. 



Toxicity. — Calmette has determined the toxicity' of several ven- 

 oms, and gives the following figures: 



1 gm. cobra or aspis kills 4000 kgm. of rabbit. 



1 gm. hoplocephaius kills 3450 kgm. of rabbit. 



1 gm. fer de lance or pseudechis kills 800 kgm. of rabbit. 



1 gm. Crotalus horrid us kills 600 kgm. of rabbit. 



1 gm. Pelias berus kills 250 kgrn. of rabbit. 



The danger of the bite depends not only upon the difference in 

 the strength of the venom of different varieties of serpents, but also 

 upon the size of the snake, the time of year and condition of hunger or 

 plenty, and particularly whether the entire discharge is injected suc- 

 cessfully or not. The fatal dose of cobra venom for an adult man is 

 variously estimated at from 0.01 to 0.03 gm., while the venom of 

 Hydrophince is about ten times as toxic; for crotalus venom the lethal 

 dose is probably 0.15 to 0.3 gm. (Noguchi). Probably in the major- 

 ity of strikes, by no means all the fluid ejected by both fangs is in- 

 jected beneath the skin of the victim. A large diamond rattler may 

 eject as much as a half teaspoonful of venom at one discharge and 

 such a dose would usuallj' l)e fatal. Repeated ejections decrease the 

 strength of the venom rapidly, until it may have almost no toxicity. 

 In general, venom is most active in warm weather and immediately 

 after the snake has fed; in winter its toxicity is slight. 



The mortality in America from snake-l)ites is very hard to ascer- 

 tain, various authors giving figures at w'ulo variance. The extensive 



»« Univ. of i'uuM. iMed. liull., 1902 (15), 300. 



'• See also lloussay and Xegrete, Revista de I'insl. l)act. Buenos Aires, 1918 (1), 

 431. 



32 Anil. lust. Paslcur, 1919 (33), ()8. 

 " Ann. (1. I'ln.st. I'ustcur, 1,S9S (12), 510. 

 ^* Jour, of IMiysiol., 1905 (32), 207. 

 ^''Jour. Infect. Dis., 1915 (17), 351. 



