An immense number of animals have been vaccinated by this method at the Pasteur Institute at Lille, where Dr. Calmette is now director; and in one of his memoirs we are told that they have horses there which have yielded during a period of eighteen months serum extremely active against venom. These horses receive in a single inoculation, without suffering the least inconvenience, doses of venom sufficient to kill fifty horses fresh to the treatment. Large quantities of this serum have been forwarded from the Lille Institute to various parts of the world where venomous serpents are most frequently met with, and already important evidence has been collected as to its efficacy in cases of human beings bitten by dangerous reptiles. So impressed with its importance are Indian medical authorities, that its preparation has been included in the work which the new great bacteriological institute at Agra is carrying on. The importance of the production _in situ_ of this anti-venomous serum has been recently demonstrated by the experiments which have been conducted in the Plague Research Laboratory, Bombay, by Mr. Lamb and his colleagues, on the keeping properties of such serums in India. From the careful investigations which have been made on this subject, these gentlemen state that anti-venomous serum undergoes a progressive and fairly rapid deterioration when stored in hot climates, and that this deterioration is greater and more rapid the higher the mean temperature to which it is subjected. The protective potency of this horse-serum may be gathered from the fact that it suffices to inject a rabbit, for example, with a quantity amounting to about one two-hundred-thousandth of its weight to ensure the latter acquiring complete immunity from a dose of venom capable of otherwise killing it in twelve hours.