POISONOUS SNAKES. 
§ 669.] 
511 
reacting two hundred times the otherwise deadly dose— e.g. the fatal 
dose for a horse is about 10 mgrms. of the dried cobra venom, and a 
horse after successful treatment will bear the injection of a quantity 
equal to no less than 2 grms. Many animals during the process die of 
endocarditis or nephritis, which affections must therefore be considered 
as true sequelae to chronic cobra poisoning. The serum obtained from 
the blood of an animal which is considered highly resistant is tested 
by mixing a definite quantity of it with an equally definite quantity of 
cobra venom, and injecting it into some small animal. The serum is 
considered sufficiently active if 2 c.c. of serum mixed with 1 mgrm. of 
cobra venom produces no poisonous symptoms when injected into a 
rabbit, and if 2 c.c. of the serum injected into a rabbit 2 kilogrammes 
in weight protects it from the effects of 1 mgrm. of cobra venom 
injected subcutaneously an hour later. 
The serum is preserved with strict antiseptic precautions in 10-c.c. 
tubes ; it is said not to lose its activity for two years or even longer. 
Another method of preserving the serum is drying it at a low tempera¬ 
ture ; it then appears in commerce as light dry yellow scales, which for 
subcutaneous use are dissolved in water at the time. For ten years 
now the Pasteur Institute at Lille has prepared this form of antitoxin ; 
at first it was hoped that in such a substance was to be found a general 
remedy for, or protection against, snake-bite, but this is not so ; its action 
is confined to either the particular species of snake venom, or species 
nearly allied, against which the horse was immunised. Experiments are, 
however, being made in order to obtain if possible a general sort of 
serum, by operating with mixtures of venoms ; whether success will be 
attained time alone can show. 
§ 669. Other Colubrine Snakes. —The venom of Bungarus fasciatus, 
or the Banded Krait, acts similarly to the cobra poison ; but since 
its activity is destroyed by heating to from 73°-75°, it is less stable. 
Bungarus cceruleus, or the Krait, one of the most dreaded of the 
Indian snakes, is said to be even more virulent than the cobra. 1 
Naja Bungarus , or the Hamadryad, possibly the largest poisonous 
snake in the world, growing to over 13 feet in length ; the Naja haje 
(Cleopatra’s asp) ; Elaps corallinus, the brilliant red coral snake of 
America ; the Elapince of Australia—all possess a venom having a 
physiological action similar to that of the cobra. 
The Viperidae. —The chief poisonous snakes belonging to the 
Viperidce, besides the true vipers, are the American rattlesnakes, be¬ 
longing to the genus Crotalus —viz. the Lachesis muta (Crotalus mutus ), 
commonly called the Surucucu, or Bushmaster of the Dutch colonists 
1 Leonard Rogers, M.D., Phil. Trans., 1904. Major R. H. Elliott and W. C. 
Sillar, M.B., ibid. Some Observations on the Poison of the Banded Krait (Bungarus 
fasciatus), by Capt. George Lamb, jM.D. Glas., Calcutta, 1904. 
