1896. ] on Immunisation against Serpents' Venom. 131 



dried and weighed each collection separately, and sent me the 

 weights. They are as follows : — 



(1) 0-726 gramme. (4) • 1 14 gramme. (7) 0-239 gramme. 



(2) 0-262 „ (5) 0-132 „ (8) 0-306 



(3) 0-115 „ (6) 0-113 „ (9) 0-253 „ 



The total venoms yield an average of 0*255 gramme for each bite ; 

 but, if the exceptionally large quantity stated in the first figure be 

 excluded, the average for the remaining eight becomes '195 gramme. 

 It must also be considered that these quantities were obtained in the 

 most favourable conditions for securing the total quantity ejected at 

 a single bite, whereas in actual practice the conditions are less 

 favourable for the insertion of the total available venom into the 

 tissues of the victim. 



Reverting now to determinations of the minimum-lethal dose for 

 the lower animals, we find that if the minimum-lethal dose for the 

 cat be adopted as being the same as that for man, the total quantity 

 of dry cobra-venom required to kill a man of ten stones weight 

 would be 'SIT gramme, which is considerably more than the 

 quantity, judging from the above averages, that a cobra is usually 

 able to eject during a single bite. It would therefore appear 

 necessary to assume that the minimum-lethal dose per kilogramme 

 for man is smaller than for a cat ; but, as it is probably greater 

 tban for a rabbit, we may for convenience assume that it is twice 

 that dose. In this case, the smallest quantity required to produce 

 death in a man of ten stones would be about '0317 gramme, which, 

 however, seems to be considerably less than the quantity which a 

 fresh cobra has at its disposal. Applying now the facts that have 

 been stated in the series of experiments where the smallest quantity 

 of antivenene required to prevent death when injected thirty minutes 

 after twice the minimum-lethal dose was determined, it will be 

 recollected that that quantity is 5 c.c. per kilogramme of animal. 

 Taking this as a basis for the dose of antivenene, in order to prevent 

 death in man from the estimated minimum-lethal dose of cobra- 

 venom, so considerable a quantity as 330 c.c, or about 11^^ ounces, 

 of antivenene would be required, if the antivenene be injected not 

 much longer than thirty minutes after the bite had been inflicted. 

 This, though a large, is by no means an impossible dose, and it could, 

 without much inconvenience, be introduced under the skin at several 

 parts of the body. 



On the other hand, the estimate which I have adopted of the 

 minimum-lethal dose for man may be too high a one, and if it should 

 prove to be nearer that for the rabbit, then the quantity of antivenene 

 required to prevent death, if administered half an hour after the 

 snake-bite, would be reduced to about four ounces. It is also to be 

 recollected that if dry antivenene be used, it may be dissolved in a 

 much smaller quantity of liquid than is required to restore it to its 

 original bulk. 



K 2 



