TOXIC SECRETIONS OF VENOMOUS SNAKES 71 



With Lachesis lanceolatus (fer de lance) Calmette gives 0.320 gm. in the 

 fresh and 0.127 g m - i n tne dried form for a single extraction from both glands. 



With Crotalus adamanteus, 1 Flexner and Noguchi put the figures at between 

 0.179 g m - an d °-3°9 g m - i n the dried form for a single extractable amount 

 from both glands. 



With Crotalus confluentus, Calmette gives 0.370 gm. in liquid and 0.105 g m - 

 in dried form from a single bite. 



With Ancistrodon piscivorus, Flexner and Noguchi estimated 0.125 E m - to 

 0.18 gm. dried as a single extractable dose. 



With Ancistrodon contortrix the same authors found the average to be 

 0.03 gm. to 0.06 gm. dried. 



With two large Egyptian Cerastes specimens Calmette derived 0.125 g m - 

 (0.027 S m - i n dry) and 0.085 S m - (0-019 g m - i n dry)) respectively. 



With Enhydrina, Rogers could extract only 0.0023 S m - to 0.0094 gm. (as 

 dried form) from both glands of the adult specimens. 



The loss in weight of venom upon drying has been estimated by various 

 authors. Weir Mitchell and Reichert found it to lie between 25.15 per 

 cent to 27.42 per cent with Crotalus adamanteus, C. atrox, and Ancistrodon 

 piscivorus. Calmette places it at 62 to 80 per cent. C. J. Martin found 

 the loss in weight after drying the Australian venom to be 33 per cent, while 

 Flexner and Noguchi found the solid portion of venom {Crotalus and An- 

 cistrodon) to range from 50 to 70 per cent of the total weight. 



TOXICITY OF SNAKE VENOM. 



Irrespective of the modes of action by which the fatal issue of the venom 

 poisoning is brought about, it is possible to determine the approximate mini- 

 mal lethal dose of each snake venom for a given species of animals by intro- 

 ducing the venom directly into the system of that animal. It may be stated 

 that certain venoms act more powerfully when introduced directly into the 

 blood circulation, while others do not appreciably differ in their final out- 

 come, whether they are given subcutaneously or intravenously. Thus, a 

 much smaller quantity of the venom of Crotalus is effective when injected 

 intravenously than when injected intraperitoneally or subcutaneously, while 

 but little difference is shown with the venom of Cobra in these respects. It 

 is superfluous to emphasize the fact that venoms from different species of 

 snakes differ slightly or widely in their constitution, which is always multiple 

 in nature, and also in their physiological effects. A powerful venom means 

 one which kills or injures the victim by a smaller amount than a weak venom. 

 The cause of these qualitative differences will be treated later in extenso. 



The susceptibility of animals to venom is also very variable. Speaking 

 in general, warm-blooded animals are more sensitive to the action of venom 

 than cold-blooded animals. There exists among various species of animals 

 a constant susceptibility peculiar to each group. 



In regard to the toxicity of venom we find certain constancy of strength in 



1 Weir Mitchell (1861) states the following details: Crotalus durisstis, No. 1, 18 in., 9J oz.; venom 11 

 drops. No. 2, 25 in., 18 oz.; 19 drops. No. 3, 49^ in., 3$ lbs.; 29 drops. 



