It is unquestionable, however, and I have personally satisfied myself of the fact, that many genuine snake-charmers go through their performances with Cobras whose poison-apparatus is absolutely intact. That they almost always avoid being bitten is due to a perfect knowledge of the habits and movements of these reptiles. Nevertheless, accidents sometimes happen to them, and every year a few of them succumb in pursuit of their calling (see p. 370). Still, it may be asserted that some of them really know how to vaccinate themselves against venom, by making young Cobras bite them from time to time. It is stated by E. C. Cotes,[88] formerly of the Calcutta Museum, that the Indian snake-charmers do not extract the poison-fangs from their snakes. Even though deprived of its fangs, the snake would still be dangerous on account of its other teeth, the punctures of which would provide another channel for the penetration of the venom. Snake-charmers pretend that they owe their immunity to graduated inoculations. This is not yet conclusively proved; what is better established is that they take the greatest care to avoid being bitten, and that in so doing they display the most remarkable skill. Even in France we are acquainted with professional viper-catchers, who employ the method of graduated inoculations in order to render themselves immune to the bites of indigenous reptiles. One of these men, who lives near Arbois (Jura), takes good care to get himself bitten, at least once a year, by a young viper; when he forgets this precaution and happens to be bitten, he always feels the effects much more severely. Fraser[89] (of Edinburgh) thinks that the repeated ingestion of small quantities of venom may suffice to confer immunity, and he mentions a certain number of experiments performed by him upon white rats and kittens, from which it would appear that the ingestion of venom, continued for a long time, finally renders these animals absolutely refractory to subcutaneous inoculation with doses of the same venom several times greater than the lethal one. He therefore concludes that this process of vaccination may probably be in use among snake-charmers. I have submitted this hypothesis to the test of experiment. I succeeded in making _adult_ rabbits, guinea-pigs, and pigeons absorb enormous doses of _Cobra_-venom by way of the alimentary canal. In this manner I have administered doses as much as a thousand times greater than the lethal one, yet I have never been able to prove that the serum of these animals became antitoxic.