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 be hutten-rauch, furnace smoke. One of the men took his dose about twice a week, the other generally once a week. They had of course begun with doses of less than a grain. It was understood to be a tonic and stimulant, and to aid the respiration in climbing. It was also believed to promote sexual desire. Having acquired the habit the occasional dose was much missed if omitted for long.

The modern employment of serums in the treatment of zymotic diseases goes a long way towards explaining the fact of the immunity of individuals in respect to bacterial poisons. But the possibility of immunity against such poisons as arsenic, opium, or serpent venom appears to rest on a different basis. In 1896 Professor (now Sir) Thomas R. Fraser, M.D., F.R.S., reported to the Royal Institution a long investigation dealing with the alleged resistant power of certain tribes or sects in India, Africa, &c., who can suffer the bites of unquestionably venomous snakes without becoming seriously affected. After quoting numerous reports from old and recent works showing that this immunity is an actual fact, Professor Fraser described a long series of experiments extending over many years with venom which he had obtained from India, America, Africa, and Australia. The venom, he stated, is a complex substance and is not a ferment. Ascertaining the minimum lethal dose for each animal he experimented on frogs, cats, rabbits, guinea pigs, and other animals, and beginning with one-tenth, one-fifth, or one-half of that dose, and gradually increasing it, he found it possible to administer four or five times, and in