438 DISEASES DUE TO J'ENOSiS AXD POISONS 



from the snakes in question, and estimating two-thirds of the quantity 



obtained as the amount which could be injected at once. The resuhs 



were : — 



Naja tripudians ... ... ... 21 1 mgm. of desiccated venom 



Bungarus candidiis ... 



„ fasciatus ... 



Vipera riisselli 

 Ecliis carinatLis 



Lachesis gramineus ... 



This was when the snakes were heahhy, in full natural vigour, not 



exhausted, roused from hibernation or in captivity. 



THE CHARACTERS OF SNAKE YENOM. 



Collect the venom bv chloroforming the snake and squeezing the 

 venom into a vessel. Dry it c{uickly in a desiccator over sulphuric 

 acid. When dry it will remain potent for years. In the fluid form it 

 is transparent, slightly 3'ellowish, odourless, acid in reaction, bitter to 

 the taste, syrupy, of a specific gravity 1030- 1060, readily soluble in 

 water or saline, rich in soluble albumins which are its toxins. All its 

 toxic substances are precipitated by absolute alcohol. The venom is 

 destroyed by strong acids, alkalies, potassium permanganate, boiling 

 or by anything that " kills " ordinary albumin. Gastric juice destroys 

 that of the Colubrinas and pancreatic juice that of the Viperin^e. When 

 dry it is not unlike iodoform in appearance. It can decompose and 

 change its colour. Light causes it to deteriorate when in the fluid 

 state, but it does not affect it when dry to any great extent. Fluid 

 venom may readily be contaminated b}' micro-organisms of all kinds. 

 Glycerine in ecjual parts is a good preservative. Its toxicity is increased 

 during starvation, and in dry climates in the same snake species. The 

 effects vary A\ith the amount injected, the species of snake, the site of 

 the injection, viz., skin, muscle, or blood-stream, and other factors. 



THE VARIETIES OF YENOM. 



Snake venoms are very complex liquids, each containing some of 

 the following active principles : — 

 (i) Neurotoxins. 



Some act on ihe vasomotor centre. 



Others act on the respiratorv centre. 



Others on the nerve endings in muscle, especiallv of the phrenics. 



(2) Agglutinins. 



(3) Cytolysins. 



Some are iKcmolvsins. 

 Others are leucolysins. 

 Others are hccmorrhagins. 

 Others are simple cytolysins. 



