22i JOURNAL, BOBiBAT NATURAL HISTORY SOCIETY, Vol. .tlV. 



Physical and Chemical Properties of Venom. 

 Fresh liquid poison is of a yellowish or straw colour. Cobra venom 

 is quite clear, while Daboia poison has, as a rule, a small quantity of 

 undissolved suspended matter. The reaction of both venoms is 

 invariably acid to litmus paper, unless there has been much admixture 

 with the alkaline secretions of the mouth. Cobra venom has a very 

 bitter astringent taste ; chewing Uaboia venom is like chewing ordinary 

 gum acacia— there is no taste at ail. 



Venom dried rapidly in a thin layer over calcium chloride cracks 

 into small pieces. In the case of Cobra poison these particles are of 

 an irratrular shape, as broad as they are long ; they are yellowish and 

 translucent. In the case of Daboia venom the cracking is more or 

 less in longitudinal strias, and, in consequence, fine needle-shaped 

 particles are found. I show you here good specimens of both these 

 varieties of snake venom. 



Thoroughly dried venoms retain their toxic power for an indefinite 

 period. They dissolve again readily and completely in water or salt 

 solution. 



It is quite unnecessary for me to enter into the complicated question 

 of the chemical constitution of these poisons. At one time, not very 

 long ago, it was thought that the toxic constituents of all snake venoms 

 were alkaloids, similar to the poisonous vegetable alkaloids, such 

 as stirychnine. This, however, has been shown to be an entirely 

 erroneous supposition ; and I think I am right in saying that all 

 investigators are agreed that all snake venoms owe their poisonous 

 properties to the proteid or albuminous substances which they contain 

 in solution — substances similar in composition to the albumen or 

 white of egg. All snake poisons ai'e, in fact, almost pure solutions of 

 proteids, and contain little else beyond a trace of inorganic salts and 

 a small quantity of an organic acid and colouring matter. Further, 

 there is no doubt that each venom contains two or more different 

 proteids, and that the physiological action of a particular venom depends 

 on the nature of the proteids which it contains. Organic chemistry 

 has, unfortunately, not advanced far enough as to be able to separate 

 in pure form these various proteids or to arrive at any estimate of 

 their chemical constitation. We have, therefore, to content ourselves 

 at present with various crude methods of studying the physiological 

 actions of the different proteids in snake venoms. 



