Chapter I (5)

In a recent address on The Chemistry of the Infinitely Little, M. Grimaux referred to the fact, with which all who have thought about it have been struck, that pathogenic microbes being diffused all through the atmosphere, everybody must breathe and absorb all sorts of them, including germs of typhoid fever, scarlet fever, diphtheria, etc., and yet we are not all attacked with those diseases. Why? Because each person has a peculiar temperament, and cells adapted, to a greater or less extent, to resist the microbe, to destroy it when it enters the organism, and thus constitutes, as the case may be, a good or a bad cultural medium. Every one, we might say, is immune against some or other of the pathogenic microbes. Like immunity belongs also to certain animal species, and if a microbe pathogenic to man or to some other species is injected into them they will resist it. The blood of refractory animals probably contains principles not yet known which oppose the development of the infectious microbe. From this fact the idea has been suggested of injecting the blood of refractory animals and communicating an artificial immunity to the individual to whom the injection is applied.

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