Although in the soul-blending at the moment of conception only the latent forces of the two parent souls are transmitted by the coalescence of the erotic cell-nuclei, still it is possible that the hereditary psychic influence of earlier, and sometimes very much older, generations may be communicated at the same time. For the laws of _latent heredity_ or atavism apply to the soul just as validly as to the anatomical organization. We find these remarkable phenomena of reversion in a very simple and instructive form in the alternation of generations of the polyps and medusæ. Here we see two very different generations alternate so regularly that the first resembles the third, fifth, and so on; while the second (very different from the preceding) is like the fourth, sixth, etc. (_Natural History of Creation_). We do not find such alternation of generations in man and the higher animals and plants, in which, owing to continuous heredity, each generation resembles the next; nevertheless, even in these cases we often meet with phenomena of reversion, which must be reduced to the same law of latent heredity. Eminent men often take more after their grandparents than their parents even in the finer shades of psychic activity--in the possession of certain artistic talents or inclinations, in force of character, and in warmth of temperament; not infrequently there is a striking feature which neither parents nor grandparents possessed, but which may be traced a long way back to an older branch of the family. Even in these remarkable cases of atavism the same laws of heredity apply to the _psyche_ and to the physiognomy, to the personal quality of the sense-organs, muscles, skeleton, and other parts of the body. We can trace them most clearly in the reigning dynasties and in old families of the nobility, whose conspicuous share in the life of the State has given occasion to a more careful historical picture of the individuals in the chain of generations--for instance, in the Hohenzollerns, the princes of Orange, the Bourbons, etc., and in the Roman Cæsars. The causal-nexus of _biontic_ (individual) and _phyletic_ (historical) evolution, which I gave in my _General Morphology_ as the supreme law at the root of all biogenetic research, has a universal application to psychology no less than to morphology. I have fully treated the special importance which it has with regard to man, in both respects, in the first chapter of my _Anthropogeny_. In man, as in all other organisms, "the embryonic development is an epitome of the historical development of the species. This condensed and abbreviated recapitulation is the more complete in proportion as the original _epitomized development_ (_palingenesis_) is preserved by a constant heredity; on the other hand, it falls off from completeness in proportion as the later _disturbing development_ (_cenogenesis_) is accentuated by varying adaptation."