CHAPTER LXXX 



VENOMS AND ANTIVENINS 



AFRANIO DO AMARAL 



Antivenin Institute of America, Glenolden, Pa. 



Venomousness is not peculiar to the ophidians alone. Throughout the animal 

 kingdom there are many species of insects, scorpions, spiders, and other invertebrates 

 and also batrachians, lizards (genus Heloderma), fishes, and even mammals that have 

 venomous qualities. Antitoxic sera or antivenins have likewise been prepared against 

 their venoms. However, snake venoms are those that have been most thoroughly 

 studied, and the corresponding antivenins have been most successfully applied in 

 practice. 



POISONOUS SNAKES AND SNAKE VENOMS 



Both from the anatomical and physiological standpoints, practically all snakes 

 should be considered poisonous. As a rule, they have a gland corresponding to the 

 parotid of mammals, and this yields a toxic secretion. From a practical standpoint, 

 however, only the proteroglyphous and solenoglyphous forms must be taken into 

 consideration, because they are the only ones that secrete an amount of venom large 

 enough to cause severe lesions or that inoculate their venom deeply into the tissues. 

 It was, indeed, simply the development of a well-differentiated inoculating apparatus 

 situated on the anterior part of the upper jaw which made biologists first distinguish 

 them from the aglyphous and opisthoglyphous snakes and consider the first two 

 groups as poisonous and the latter as non-poisonous. 



Of the proteroglyphous series I recognize two valid and well differentiated 

 families, the Disteiridae and the Elapidae. The former are marine and live in the 

 Pacific and Indian oceans; only one species lives in fresh water. The Elapidae, also 

 proteroglyphous, are all terrestrial and in general are found all over the world except 

 the northern portions of the Holarctic region. They represent by far the greater part 

 of the ophiological fauna of Australia. To this family belong the dreaded "cobra" 

 of Asia and Malay, the "coral snakes" of the Americas, and the "tiger snake" of 

 Australia, The solenoglyphous forms comprise the Viperidae and the Crotalidae. The 

 Viperidae, which are peculiar to the Palaearctic, Ethiopian, and Oriental regions, 

 are represented by the vipers of Europe (genus Vipera), Asia (genus Daboia), and 

 Africa (genera Cobra, Bids, etc.). 



The Crotalidae, also solenoglyphous and distinguished from the preceding family 

 by having a facial pit, live in the eastern Palaearctic but more especially in the 

 Nearctic and Neotropical regions, where they make up the majority of the poisonous 

 species. Their various genera are the following: Trimeresicrus Lacepede, which is 

 peculiar to Asia; Bothrops Wagler, which is found chiefly in Central and South 

 America, in the West Indies, and tropical Mexico, its most important representative 



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