These are truly what the biologists call sports; and to those classes of sports that occur as specially gifted in human culture, in the varied fields of science, art, or literature, we assign such a person as Shakespeare, and call the remarkable variations embodied in him genius. On the other hand, such variations as lead to certain forms of pigmentary degeneration of the retina, and to Daltonism, to dyschromatopsia and achromatopsia, to certain supernumerary glands, polydactylism, and such like, which are either useless or harmful, we designate as pathological cases or monstrosities. Hereditary units (the carriers of heritages) may be _latent_—that is, they may appear late in life, or in the offspring, or, still again, in remote descendants; in the latter cases the heritages are spoken of as reversional or _atavistic_. Latent hereditary units may very usefully be compared to dormant seeds buried in the ground. It is stated that buried seeds may lie dormant for many years, so that when a plot of ground is plowed deeply and upturned, plants that have not been seen there within the memory of one will often make their appearance and flourish. The hereditary units are veritable _living seeds_, that, under certain and often unknown stimuli, grow and unfold their heritages as do the buried seeds. Latent heritages are well illustrated by a study of secondary sexual characters as developed at puberty. Among our barnyard fowls, the hens often, when they have atrophy or degeneration of the ovaries, although up to this time they have laid eggs for years, stop this function, put aside the plumage and appearance proper to their sex, and don more or less completely the garments of the rooster. Thus females have latent in them many secondary sexual characters of the male. For similar reasons the male develops, occasionally, female characters. This latency is illustrated again in deer. In most species of the deer tribe the males alone possess antlers, yet it is a well-known circumstance that in females with degenerations of the ovaries rudimentary horns that are never shed appear. A study of congenital color-blindness illustrates beautifully latent heritages, showing how the females of one generation may be free from the malady and the males of the next afflicted. A study of the _regeneration of lost parts_ in various animals and plants illustrates well the latency of many hereditary units. A cutting made from the willow and planted sends out roots and finally reaches the dimensions of the adult tree. Here the body cells of the stem evidently contained, in a latent condition, many hereditary units in their nuclei, which became active through the special stimulus of being planted as a cutting. Adult plants can be raised from the cuttings of many other plants.