150 PHYTOTOXINS AND ZOOTOXINS 



prepared by Noguclii.*'' This crotalus antivenin also neutralizes 

 hemolysins of various venoms, and also of snake serums. 



Presumably antivenin neutralizes venoms in exactly the same way 

 that antitoxin neutralizes toxins; i. e., cell receptors are thrown off 

 from the injured cells during immunization, which combine with 

 venom amboceptors in the blood, and thus prevent their combining 

 with the cells. Antivenin also prevents the inliibiting action of venom 

 on bactericidal serum, indicating that it prevents the venom ambo- 

 ceptors from binding the serum complement. The reaction of venom 

 and antivenin is certainly a chemical one, being likened bj' Kyes^- 

 to that of strong acids upon strong bases. 



The serum of animals immunized to venoms contains precipitins 

 for the proteins of these venoms, and, to some extent, for the serum 

 proteins of the same species of snakes. These precipitins are highly 

 but not absolutely specific, and they bear no exact quantitative rela- 

 tion to the other antibodies present in the same sera.^^ 



As is well known, snakes are nearly or quite insusceptible to snake 

 venom. Cunningham^* found that serum of cobras was devoid of 

 antitoxic property, so the immunity of snakes must be ascribed to an 

 absence of cell receptors in their tissues, with which their venom am- 

 boceptor can combine. The reputed immunity of the mongoose and 

 hedgehog depends partly on a relatively low susceptibility, but prob- 

 ably more on the agility of the mongoose and the defensive spines of 

 the hedgehog. 



Platypus Venom. — The only mammal with a venomous secretion is that strange 

 freak, the duck-billed platypus {Omithorhynchus paradoxus). The males have a 

 hollow movable spur on each hind foot, communicating like a fang with the venom 

 gland, which secretes a venom with properties resembling the venoms of the 

 Australian snakes, but much weaker. 



Scorpion Poison " 



This poison is secreted by a pair of specialized glands in the pos- 

 terior segment of the elongated abdomen, surrounded by a firm cap- 

 sule with a sharp apex through which the poison is discharged. Its 

 effect on man is usually confined to local pain, swelling, and occa- 

 sionally phlegmonous inflammation with constitutional symptoms 

 after bites from the largest species. In Africa a large scorpion {An- 

 drocionus) exists, that is reputed frequently to cause fatal poisoning, 

 especially in children. Manchuriaii scorpions {Buihus martcnsi, 

 Karchi) seem to be less toxic than this or Mexican scorpions {Centi'urus 



«i Univ. of Penn. Med. Bull, 1901 (17), 154; Jour. Expcr. Med., 1906 (8), 614. 



«- liorl. kliii. Woch., 190 t (11), 494. 



*^ See lloussay and Negrcte, Hev. inst. bact. Buenos Aires, 1918 (1), 15. 



«' Nature, 1S9() (55), 139. 



*"* A comi)l('to discussion of the literature on i)ois()nous invertebrates, etc., is 

 given by v. Fiirth, " N'crglcicliende chemische IMiysioldgic dcr niedcren Tiere," 

 Jena, 190.'}; and by Faust, "Die (icrisclicn (Jifte," liraunschweig, 190(). Con- 

 cerning scorjjions see Kubota, .Jour. I'li.irriiacol., 191S (11), 447. 



