8ECBETI0N AND COLLECTION OF VENOM IN SNAKES 149 



The quantity of venom secreted by the glands varies greatly, 

 according to the length of time which has elapsed since the animal 

 took its last meal, and in accordance with a number of other con- 

 ditions not very easy to determine. 



The Common Viper of Europe yields scarcely 10 centigrammes 

 of poison, while an adult Indian Cobra may excrete more than 1 

 gramme. 



Freshly collected venom is a syrupy liquid, citron-yellow or 

 slightly opalescent white in colour. 



When dried rapidly in vacuo or in a desiccator over calcium 

 chloride, it concretes in cracked translucent lamellae like albumin 

 or gum arable, and thus assumes a crystalloid aspect. In this 

 condition it may be kept indefinitely, if protected from light, air, 

 and moisture. It dissolves again in water just as readily as 

 albumin or dried serums. 



I regularly weighed the dry residue from eleven bites made 

 on a watch-glass by two Naja haje, received at my laboratory from 

 Egypt at the same time, and placed in the same case. Both snakes 

 were approximately of equal length, 1,070 millimetres. Through- 

 out the entire course of the experiment, which lasted one hundred 

 and two days, neither of them took any food, but they drank water 

 and frequently bathed. 



The results that I obtained are shown in the table on next page. 



It will be seen that in one hundred and two days, an adult Naja 

 haje is capable of producing on an average 0-632 gramme of liquid 

 venom, equal to a mean weight of 0-188 gramme of dry extract ; 

 and we may conclude that 1 gramme of liquid gives 0-336 gramme 

 of dry venom. 



In Australia it has been found by MacGarvie Smith, of Sydney, 

 that Pseudechis porphyriacus yields at each bite a quantity of 

 venom varying from Q-lOO gramme to 0-160 gramme (equal to 0-024 

 gramme to 0-046 gramme of dry venom), and that a Hoplocephalus 

 curtus (Tiger Snake) yields 0-065 gramme to 0-150 gramme of 



