disturbance of the system produced by them is small when compared to the disturbance produced by the toxins of acuter diseases—e.g. anthrax or diphtheria. The microbes, therefore, since Natural Selection has so little developed their toxins, and since they are able so long to resist the phagocytes, must, like those of tuberculosis, possess considerable "personal vigour," and must therefore considerably injure and enfeeble the phagocytes in the physical struggle waged between them. As a result, the phagocytes of an infected individual are at a great disadvantage, as compared to the phagocytes of an individual in whom the toxins alone are present, and therefore are much less able to vary in a fit direction, are much less able to respond appropriately to the stimulation of the toxins; so that when, at a given stage of the disease, the phagocytes of the latter, uninjured by a physical struggle, are quite able to destroy the microbes, should they find entrance, the phagocytes of the former are quite unable to do so speedily, and recovery from the disease is delayed to a later period.
Children born of parents recovered from syphilis and immune to it are not themselves immune, though noninfected children born of a mother not yet recovered are certainly immune, as we may prophesy with confidence. Here again we light on a fact of the highest importance, the significance being this—that while in the noninfected embryo of a diseased mother there are phagocytes which react to the stimulation of the toxins derived from the microbes in the mother, whereby the immunity of the child is secured, in the ovum (or the spermatozoon) of an infected person there are no phagocytes; in it therefore there can be no fit reaction, and therefore the individual into which it may subsequently proliferate is not immune.
