CHAPTER VII. 



PHYSICAL AND CHEMICAL PROPERTIES OF SNAKE VENOM. 



The venom of the snake in the fresh state is a somewhat viscid fluid of a 

 yellowish tint, which varies in intensity from the palest amber (often more or 

 less greenish) to a deep yellow. The specific gravity ranges from 1.030 to 

 1.070. 1 In fresh venom there are floating granular particles, which soon 

 settle down to the bottom of the receptacle. The amount of the suspended 

 particles varies at different times, being more abundant when we squeeze 

 the poison glands forcibly. These particles are whitish and under the micro- 

 scope are seen to consist of epithelial cells, cellular debris, and some granula. 2 



The reaction of venom to litmus is usually acid, and is alleged to be fainter 

 in the colubrine than in the crotaline venoms. According to Weir Mitchell 

 the reaction of crotalus venom is invariably acid, 3 and the author has met 

 the same result. In some instances it may be neutral. The taste of venom 

 is described by Mead as acrid or caustic to the tongue, while Fontana simply 

 perceived a benumbing effect on the part on which it was placed, and Jetter 

 confirmed his experience. Weir Mitchell found no such taste or sensation in 

 crotalus venom. Calmette describes venom as having a bitter taste. The 

 peculiar odor, often attached to venom, has its origin in the snake itself. 



The amount of yellow pigment in venom is not always the same, as each 

 individual snake has its own intensity, but no color is peculiar to any definite 

 species. It has frequently been observed that one specimen furnishes a deep- 

 colored venom, the other a very pale-colored venom. The amount of yellow 

 pigment is gradually reduced by repeated extraction of venom from a snake 

 which refuses to feed in captivity. No total disappearance has been observed. 

 The author has once seen colorless secretion by a few specimens of banded 

 rattlesnakes (Crotalus horridus) kept in captivity, and thought it a specific 

 characteristic, but later, while collecting venom from another group of speci- 

 mens belonging to the same species, found it to be quite yellow. 



When mixed with water venom diffuses an opalescent tint through it, and, 

 on standing, a considerable amount of whitish deposit settles, consisting of 

 proteins, or protein-like substances, chiefly globulins, mucin, epithelia, and 

 their debris. In a weak neutral salt solution venom produces but little 



1 Weir Mitchell: Crotalus horridus 1.054; C. atrox 1.077; C. adamanteus 1.061; Ancistrodon piscivorus 



1.032. Wall: cobra 1.058. 



2 These particles, or rather deposit as a whole, are found to be innocuous when freed from the soluble 



constituents of venom. 



3 Weir Mitchell states that the reaction of the mouth of Crotalus is always alkaline, and suggests the 



possibility of neutralization taking place when the poison accidentally reached the mouth. 

 Mitchell emphasizes the non-volatile nature of the acid, while Calmette makes a contrary state- 

 ment, as he found the acidity disappears on drying. 



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