422 THE SNAKES OF SOUTH APRICA, 
“The second point, namely, the amount of venom which a 
snake can inject, has been settled in the case of (Indian) Cobra 
and Daboia venoms by actual experiment. In the Cobra the 
amount varies from 200 to 350 mgrms. of dried venom, and 
in the case of the Dobaia it is somewhat less, viz. 150 to 250 
mgrms. These observations were carried out on snakes freshly 
caught. 
‘““Calmette has made a series of experiments with Cobras 
which had evidently been kept in captivity for some time ; 
the greatest amount of dried venom which he was able to 
procure was 48 mgrms., and the average amount was about 20 
mgrms. 
“The therapeutic dose of serum recommended by him is 
calculated on this basis, and is evidently, therefore, much too 
small. Itis obvious that in estimating the dose of anti-venomous 
seruin to be used in the treatment of any case, say of Cobra bite, 
it should be borne in mind that the snake may have injected as 
much as 350 mgrms., for the neutralization of which quantity, 
sufficient serum must be injected in order to save the patient’s 
life. There must be, of course, many cases in which less— 
probably a good deal less—venom would be injected, and a smaller 
amount of serum would then suffice ; but there are no means by 
which this point can be estimated, and as treatment must be 
immediate there is no time to wait and watch the development 
of the case. 
“The third factor, the amount of venom a man can survive, 
must next be considered. This, of course, can only be estimated 
roughly by experiments on animals. Basing our calculations 
on results obtained with monkeys, we have arrived at the con- 
clusion that for an average man the lethal dose of (Indian) Cobra 
venom: would be about 15 to 20 mgrms., and of (Indian) Daboia 
venom about 60 mgrms. A man would therefore be able to 
survive slightly less than these amounts. 
‘Having as far as possible arrived at the data on which 
the dose of serum to be used in any case of Cobra or Daboia 
bite rests, we shall have to calculate what this dose ought 
to be. 
“Tn the case of a Cobra bite, supposing the serum to be of 
such strength that 1 c.c. is able to neutralize 1 mgrm. of pure 
Cobra venom if the snake has injected the maximum of poison, 
