In a similar manner Rennert[87] has shown that lead-poisoning occurring in the mother is apt to produce macrocephalism with frequent idiocy in the child. This brings the observer face to face with the problem of morbid heredity. It may at once be admitted that, as has been claimed by a large number of observers, morbid heredity, especially in its graver forms, is much less frequent than at first would be expected. J. P. Gray, of Utica, New York, went so far as to claim that disease is never transmitted, but this is contradicted by his own hospital reports, which, to the day of his death, contained a table headed, "Statistics of hereditary transmission of the disease." It is true, however, that the descendants of a victim of morbidity or abnormality do not always exhibit the morbidity or abnormality of the ancestor. In some cases all apparent morbidity or abnormality is wanting. In other cases slighter abnormalities are to be detected. Here the observer is brought face to face with the operation of two general principles which are interdependent: the transmutation of heredity and atavism, or "throwing back" as the cattle breeders call it. Tennyson voices the general erroneous opinion of the always evil effects of atavism in his "Locksley Hall Sixty Years After":-- "Evolution ever climbing after some ideal good And Reversion ever dragging Evolution in the mud." As Kiernan has shown, atavism at times tends to preserve the type, and offsets the influence of degeneracy. This element of atavism underlies not merely the production of the sound scions of degenerate stock, but also those in whom the degeneracy affects the earlier and not the later acquirements of the race. The contrast of the moral imbecile who is unable to acquire an idea of right, or the idiot of the lowest grade who can hardly be taught to keep himself clean, with the otherwise sound, sane, able victim of hereditary gout, is very great. Yet all the links of the chain connecting, in the same family, these contrasted types, can often be found. The law laid down as to absolute extinction through degeneracy by Morel and others can only be regarded as absolutely true when applied to a given type rather than the race as a whole. Indeed, environment may play a part in preserving a degenerate who would otherwise die out. Thus in societies at a certain stage of culture imbeciles, paupers, lunatics, and congenital criminals live at large and even propagate through legal marriage. The seemingly enormous increase of the defective class which occurs in frontier communities when the classes begin to be placed in public institutions is an excellent illustration of this.