THE RENDERING OF ANIMALS IMMUNE. 123 



have already been obtained, but in order to carry the protection to fifty 

 times the minimum lethal dose, another 30 g. would be required. I have 

 reason to hope that the India OfiSce will succeed in making arrangements for 

 procuring even this large quantity. 



The subject is one of practical importance to India, where the destruction 

 of human life by venomous serpents is represented by an annual mortality of 

 20,000, and where the failure of all methods of treatment^ has led to the in- 

 troduction of a system of extermination of venomous serpents— apparently 

 futile in its results—in the carrying out of which large sums of money have 

 been expended. 



In considering the probabilities of success by antivenene treatment, it is 

 also to be recollected that antivenene can be obtained even more powerful 

 than that which was used in the experiments which have been described, and 

 that, judging from the statistics of Fayrer and Wall, in 75 per cent, of fatal 

 cases in man death does not occur until from three to twenty-four hours 

 after the infliction of the bite. This latter fact appears to indicate that in 

 the great majority of the fatal cases the dose of venom does not much exceed 

 the actual minimum lethal^ and, therefore, is not so large as the doses: .whose 

 lethal action has been prevented from occurring in the experiments that have 

 been described, in which, further, the conditions of success in preventing 

 death were not the most favourable that could have been adopted. 



It appears to me, however, that an interest and importance as great as that 

 which can be derived from this practical application of the facts is to be 

 found in their relation to the cause and treatment of many of the most fatal 

 diseases— those, namely, which are produced by organisms that have found 

 their way into the body. The evidence in favour of the curative value of 

 the antitoxins derived from animals immunised against the toxins of these 

 diseases seems to receive an additional confirmation from these facts. They 

 also bring distinctly before us the circumstance that there are limits to this 

 curative power dependent on the dose of the toxin to be counteracted, on the 

 special antidotal activity of the antitoxin that is used, and on the duration 

 of the time during which the toxin has had an opportunity of exerting its 

 poisonous action before the antitoxin is administered. If these and other 

 conditions interfering with successful treatment are not determined and 

 recognised, unmerited discredit is likely to be attached to remedies which 

 alone of all remedies may be capable of preventing death in these diseases 

 by counteracting the effects of minimum lethal and larger doses of the toxin. 



^ "After long and repeated observation in India and subsequently in England, I am 

 forced to the conclusion that all the remedies hitherto regarded as antidotes are absolutely 

 without any specific effect on the condition produced by the poison." — Sir Joseph Fayrer on 

 the Nature of Snake Pohon, 





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