To these special causes of infectious disorders—invasion by microbes and their intra-organic evolution—hygiene is able to oppose a number of means of protection or defense; this is the part of prophylaxis. The physician can, besides, assist the organism to make a victorious struggle against the microbe; this is the part of therapeutics. On these two points, also, social influences have an extremely active effect. These interventions may be greatly modified by the position of the subject in society, and rendered, according to circumstances, insufficient and illusory, or more efficacious and even potent.
The facts thus far glanced at in this rapid review relate only to isolated cases, or to diseases which reach and kill only a few subjects. Suppose, however, these pathogenic influences raging at their extreme height; we shall then be dealing with epidemics carrying men off by thousands, by hundreds of thousands, as actually takes place with cholera, yellow fever, and the plague. Under such circumstances the microbe performs destructive work, carries death abroad, and decimates populations.
So we are brought back to the beginning of this discussion; and, examining philosophically this phase of the complex question of the office of the microbe in society, we are able to answer Broca's question, quoted at first, "What will take place in future generations when they shall have exhausted the temporary resources of emigration?" We say: Then the microbe will intervene, as it does periodically; it will decimate populations and will sow death; but it will be to renew life by enabling new existences to take the place of those which have become extinct, and by furnishing them, under an assimilable form, the organic matter which they will require for their life and healthy growth.
We thus see, even from this rudimentary sketch, that the function of microbes in society is very important. Good or evil, useful or injurious, they all have a part which is indispensable to the regular evolution of social bodies. Moreover, paradoxical as the assertion may at first sight appear, I believe the fact has been rigorously demonstrated, and may be formulated in the words, that society can not exist, live, or subsist except with the aid of the constant intervention of microbes, the great purveyors of death, but also the dispensers of matter, and therefore all-potent purveyors of life.—Translated for The Popular Science Monthly from the Revue Scientifique.
