“Two parallel incisions, 5 millimetres in length, are made in the skin, and into these is introduced the paste containing the poison. These incisions are made on the arms, near the junction of the radius and ulna with the carpal bones, on the back of the hand, on the back, on the shoulder-blades, and on the feet, near the great toes. After the operation the natives exact an oath that the vaccinated one will never kill a poisonous snake, because they say that henceforth the snake is his intimate friend, and they throw upon him an Alcatifa snake, which does not bite him. “After undergoing this operation my whole body was swollen up for a week, and I underwent every possible kind of suffering. “I have never been bitten by any snake, and cannot vouch for the infallibility of this remedy. The Vatuas do so, however, and they never kill a snake. “A short time after having been vaccinated, I was stung, when in the Seychelle Islands, by a scorpion, which did me no harm. Ten years later, at the time of my journey across Africa, I was stung by another scorpion which hurt me dreadfully, and for a week I thought that I was going to die or lose my arm.” Mystification and superstitious ideas play, as we see, a very great part in this preventive treatment, which is undergone by the natives of certain countries and snake-catchers or charmers. But it is not very surprising that, thanks to successive and repeated inoculations, a man can succeed in acquiring sufficient immunity to preserve himself from snake-bites. In ancient times it was even pretended that it was possible for this immunity to be transmitted in certain cases by heredity, and thus we can understand how the profession of snake-charmer was hereditary in certain native families in India or Egypt. With reference to this subject, Professor Landouzy, in his fine work on serum therapeutics, quotes a passage from “The Pharsalia” of Lucan describing, in the year 60 A.D., the customs of the Psylli, a people encountered by the army of Cato during its sojourn in Africa. This passage is so interesting that I cannot refrain from reproducing it:--