SNAKES OF CEYLON. 513 



and the imperfect blending is marked by an aperture. The 

 canal terminates near the point of the tooth in a minute 

 opening. 



The fangs in vipers are very mobile, or to speak more 

 correctly, the maxillae are, for the fangs are fitted into these 

 bones. Russell's viper, like other vipers, when it yawns, 

 frequently rocks its maxillse forwards and backwards. 



(b) The Glands : These sacs, compared with the cobra's, are 

 small and present a corrugated appearance unlike the smooth 

 retort-shaped glands of the cobra. Wall (A. J.) mentions a 

 supplementary gland in this viper, globular in form, which 

 completely surrounds, and empties itself into the ducts 

 draining the major sac. 



(c) Physical Characters : Lamb tells us that this venom is 

 clear, with a small quantity of undissolved material in sus- 

 pension. Its reaction is acid. The taste resembles gum 

 acacia. In drying it cracks into longitudinal fissures, yielding 

 needle-shaped fragments. The dried product retains its 

 toxic properties indefinitely, and is readily soluble in water. 



(d) Yield : Acton and Knowles obtained 145 mgms. of the 

 dried product from an adult 1,015 mm. (3 feet 4 inches) long. 

 Elliot expressed eleven drops from the two glands of an adult. 



(e) Amount injected at one Bite : This has been estimated by 

 Acton and Knowles as about 72 mgms. of the dessicated 

 poison, which is considerably in excess of the lethal dose for 

 man. 



(/) Toxicity : When swallowed daboia venom has no more 

 deleterious effect on the system than cobra poison, but, of 

 course, one must postulate a healthy and unbroken surface in 

 the mouth and further passages. Elliot gave 11 drops to a 

 goat, and a larger quantity to a dog, without noticing any ill- 

 effects. Absorbed into the blood stream, Acton and Knowles 

 find it is less than one-third as toxic as cobra venom to 

 monkeys. 



(g) Lethal dose for Man : Acton and Knowles, postulating 

 a susceptibility in man equal to that of monkeys upon which 

 they experimented, estimate the fatal dose for a man at 42 

 mgms., or about four-sevenths the approximate dose delivered 

 at one bite. 



