1896.] on Immunisation against Serpents' Venom. Ill 



understand how serpents could escape the absorption of their own 

 venom through mucous surfaces, even admitting that absorption of 

 venom does not occur in normal conditions of these surfaces. Venom 

 must, however, be so frequently introduced into their bodies, in situa- 

 tions where absorption could not fail to occur, by the bites inflicted 

 upon them by other serpents, that the conclusion seems inevitable 

 that they possess some protective quality, without which, probably, 

 no venomous serpents would now be in existence. Not only have 

 many general observations been made in favour of this belief, but it 

 has been supported by direct experiments, such as those made by 

 Fontana of Tuscany more than a century ago, and by Guy on, 

 Lacerda, Waddell, Kaufmann, and Sir Joseph Fayrer. 



This, and other evidence, pointing to the existence of protection 

 against venom, not only in serpents themselves, but also, in certain 

 exceptional circumstances, in human beings, several years ac^o ori- 

 ginated a wish to investigate the matter. It was obviously suggested 

 that if protection occurs, it must be caused by some direct result of 

 the absorption of venom ; and, therefore, that its existence could be 

 proved or disproved by experiment. In the former event, the first 

 steps would already have been taken to obtain, by further experi- 

 ments, results likely to be of value in the treatment of poisonino- by 

 serpents' venom, and, indeed, likely to be of suggestive importance in 

 even the wider field of general therapeutics. 



The general plan to be followed in the first stages of the investi- 

 gation was obviously suggested by some of the statements I have 

 reproduced ; for they indicate that individuals might become accus- 

 tomed to, or protected against the effects of serpents' bites, by the 

 introduction into their bodies of a succession of doses of venom, 

 no one of which, necessarily, at the beginning of the process, was so 

 large as the minimum-lethal. A consideration also of the facts, 

 proving the possession of protection on the part of venomous serpents 

 themselves, indicated the same plan of procedure ; for, equally 

 obviously, these serpents, from an early period of their existence, 

 must absorb venom from their own gradually-developing poison- 

 glands, until, in the course of time, they had acquired sufiicient 

 protection to remain unaffected by the larger quantities which the 

 now fully-developed glands would introduce into their bodies. 



My first supplies of cobra venom were obtained in 1869, from 

 the late Dr. Shortt, of Madras, and in 1879 from Surgeon-Colonel 

 Moir, of Meerut. They were in very small quantity, but with them 

 1 was able to satisfy myself that, by a succession of minute doses, 

 animals became able to receive the minimum-lethal dose without any 

 distinct injury. At this point, however, the supply of venom failed, 

 and the observations could not then be carried further. It became 

 evident that until large quantities of venom had been obtained, 

 definite results could not be hoped for. 



It was not until several years afterwards that a sufficient supply 

 had been gradually accumulated, by further small quantities received 

 from Sir Joseph Fayrer, the Thakore of Gondal, and Dr. Phillips ; 



