244 VENOMOUS SNAKES AND THE PHENOMENA OF THEIR VENOMS 



at somewhere from 0.015 to - 02 g m -> an d for daboia venom at 0.06 gm. 

 Although no estimates of the toxicity of the venom of Crotalus adamanteus 

 have been made on monkeys, the minimal lethal doses of this venom deter- 

 mined on rabbits, guinea-pigs, and rats by subcutaneous administration are 

 10 to 20 times larger than those of Naja tripudians, also determined on the 

 same species of animals in the same manner. It is therefore a fair approxi- 

 mation to place the minimal lethal dose of crotalus venom for a man at 0.15 

 to 0.3 gm. Of course the local disturbances caused by even much smaller 

 doses of this venom would be extremely grave, if not fatal. This estimate 

 appears to be in harmony with the statistics of mortality in man, as Weir 

 Mitchell recorded only i death out of 8 cases of rattlesnake bite. 



Now returning to the dosage of antivenins, we need only to neutralize the 

 quantity of venom which would be beyond what a man could tolerate with- 

 out death. Thus in the case of cobra bite one has to neutralize nearly 0.200 

 to 0.350 gm., which means the quantity of the present cobra antivenin approxi- 

 mating 350 c.c. 



In the case of daboia bite at least o.i gm. of the venom would be in excess 

 of the reasonable tolerance of a man, and hence it would be necessary to inject 

 loo c.c. of the daboia antivenin at once. 



In the case of crotalus bite the fatal issue may or may not follow in an 

 adult, but about 0.05 to o.i gm. may be injected in excess of toleration. The 

 present antivenin, which is still in course of preparation and is expected 

 to exceed all previous preparations in its antitoxic units for we now possess 

 a sufficient supply of the venom, which we never had before will require 25 

 to 50 c.c. to prevent death. The dosage of the crotalus antivenin is still an 

 undetermined factor, but we may confidently expect a preparation at least 

 many times more powerful than those obtained with insufficient injections 

 of the venom. 



With crotalus venom another important fact must not be neglected. It is 

 the local disturbances of the site and whole surrounding region of the bite. 

 I believe, however, that by the prompt and appropriate application of the 

 crotalus antivenin, which contains much antihaemorrhagin, this will also be 

 treated effectively. 



Taking up the cases of cobra and daboia poisonings, we have seen that in 

 order to prevent death in man at least 350 c.c. of the cobra antivenin and 

 loo c.c. of the daboia antivenin must be immediately injected intravenously, 1 

 because the above dose is calculated from the neutralizing powers in vitro. 

 Should the symptoms be already manifest the quantities of these antivenins 

 must accordingly be many times increased. Again, if the serum be admin- 

 istered subcutaneously the dosage must be increased 10 to 20 times, and this 

 would mean the injection of 3,500 to 7,000 c.c. of the cobra antivenin at once! 



1 Martin once made a statement that the quantity of antivenin sufficient to neutralize a given amount 

 of venom mixed in vitro can neutralize the same quantity of venom in vivo, if the latter be in- 

 jected subcutaneously and the former intravenously. But Martin and Lamb in their joint 

 article state that 10 to 20 times the quantity of antivenin must be injected intravenously in order 

 to effect neutralization of the same amount of venom as in the case of test-tube mixture. 



