KFFKCTS VV SNAKI'; \l':.\ ( ) M S OX DOM i:STK' ANIMALS. 34I 



alkaloid nature of venoms projiounded l)y Hlyth and Gautier was 

 disproved. In 1892 Martin and Smith, studying the venom of 

 Australian snakes, came to the conclusion that the venom con- 

 tained three proteids, a hetero- and proto-proteose, and an albu- 

 men, the hetero-proteose alone heiui^- virulent. 



During this period, which may l)e termed "the one-venom 

 period," there was a general belief that all snake venoms had 

 virtuallv the same active ])rinciples, which were thought to be of 

 a i^roteid nature, and that differences in the effect j^roduced in 

 animals bitten were ])rinci])ally due to variation in amount of 

 venom injected, thus being merely a quantitative difference. 



The next period, which may be termed "the period of more 

 than one venom," extends up to the ])resent time, in which it is 

 considered that there are at least two separate types of venom, 

 one of which may be called the Viperine type, having as its 

 example Vipcra RusscUii, and the other the ("olubrine type, which 

 may be exemplified by the Naja tripitdiaiis. There are, in addi- 

 tion, however, venoms which show characteristics of both types, 

 and in which either the ("olubrine or \'i])erine element may ]ire- 

 dominate. 



It was shown b}' Tveicliert and Weir Mitchell that there was a 

 considerable dift'erence 1)etween the venoms of \ i]X'rinje and 

 Colubrines, and Martin, working with a Colul)rine { Pscudcch: -"^ , 

 discovered that the venom prodttced intravascular clotting, and 

 suggested this action as an explanation of sudden death resulting 

 from the venom of i'ipcra Rnsscllii. This theor}- was later con- 

 firmed by Lamb and Hanna. 



In 1902 Flexner and Nogttchi i)ublished a paper on venoms, 

 showing that, in addition to the neurotrophic i)rinciples, venom 

 contained separate Ivsins for the erythrocytes and leucocytes, 

 and agglutinins for the erxthrocvtes and leucocytes, which were 

 probably identical. 



They also noted that \-en()m contained h;emorrhagins. and 

 lessened the bacterial action of the blood. 



The work (jf various investigators has shown th;it snake 

 venoms are \'ery complex li(juids containing- some of. but not all 

 in any one venom, the following active ]~)rinci])les : — 



(1) Neurotoxins — 



(a) Acting princi])ally ovi the respiratory centre; 

 ( b ) Acting principally on the vaso-motor centre ; 

 ( (• ) Acting princi])ally ujjon nerve and plates in striated 

 nuiscle, ];articularly iii tliose of the phrenics 



(2) Agglutinins. 



(3) Cvtolysins — 



( (/ ) Hsemolysin.^ ; 

 ( b ) Leucolysins. 

 ( c ) Hsemorrhagins. 



(4) A fibrin ferment. 



(5j A proteol} tic ferment. 



(6) Antibactericidal substances. 



