Upon the combination of all the different points of beauty in a single individual depend Quétélet's biological theories of the medial man (l'homme moyen), lately revived and extensively developed by Viola. The new importance acquired by the reconstruction of the medial man is due precisely to the fact that the new method of reconstructing him is by bringing together all the single characteristics taken separately and worked out mathematically according to the laws of individual variations that behave precisely like those of probability. (See Biometry and the Theory of the Medial Man.)
Viola considers, in its relation to the physiological laws of health, the combination in a single individual of the maximum number of average characteristics, which at the same time are the characteristics numerically prevalent in individuals (dominant characteristics?). The man who accumulates the greater number of average characteristics, escapes diseases and predisposition to disease; he is consequently sounder and more robust and handsomer. De Giovanni, on the contrary, through an ingenious conceit, bestows the name of morphological combination upon the union in a single individual, of parts that are mutually inharmonic and incapable of performing their normal functions together, in consequence of which such an individual's morphological personality is predisposed to special maladies.
Accordingly the meeting and union of germinative potentialities may be either more or less propitious; as for instance the result sometimes produced by the combination of a platyopic (broad) face and an aquiline and extremely leptorrhine (narrow) nose; in other words, combinations that are discordant from the æsthetic standpoint, but harmless as regards health; or again, there may be a lack of harmony between the internal organs, incompatible with a healthy constitution. There may even exist malformations due to the meeting of forms that clash violently; each of which parts may be quite normal, when considered by itself, but cannot adapt itself to the other parts with which it is united.
It is as though the dominant characteristic in respect to an organ had been overpowered by another, which ought on the contrary, in this special case, to have been recessive.
It is precisely on this question of the dominance of characteristics that the researches of the Mendelists are at present being expended. It has been observed in the course of experiments that there exist certain special correlations between potentialities, in consequence of which certain characteristics must always go together; as, for example, when two characteristics, having once been united, must continue to recur together, although they each exist separately. These laws, which are not yet clearly determined, may serve to explain the final harmony of the sum total of individual attributes.
But in general the dominance of characteristics is not absolute, but subject to many causes of variation, associated with environment. Thus, for example, just as a change in nutrition of a young plant will result in a different height, it is also possible in the mechanics of reproduction that the original relations of germs may be altered by external causes, and the dominant characteristics be made recessive.[6] Many deviations are attributable to the influences that act upon the germinative cells of hybrids, after the latter have already been determined in their potentiality; thus for example when certain germinal cells are less resistant during maturation; or again when combinations between potentialities are difficult to achieve. That is to say, there may exist certain phenomena associated with environment, thanks to which Mendel's natural laws concerning the dominance of characteristics may become inverted.
Another fact of great significance is this: that, in the course of extensive experimental plantings, for the purpose of verifying the laws of Mendel, a widespread sickliness and mortality occurred among cryptograms, at the expense of the plants of recessive character; which would go to prove that a lower power of resistance accompanies the appearance of recessive characteristics. The dominant characteristics accordingly are not only the most highly evolved, but they also possess a greater power of resistance. So that, to-day, the dominance of the strong tends through the workings of the phenomena of Mendelism, to do away, little by little, in the course of generations, with characteristics that are weak or antiquated. This has an important bearing upon human pathology, because it opens the way to hope for a possible regeneration in families branded with hereditary disease.
The germinal potentialities that contain beauty and strength seem predestined to that predominance which will achieve the triumph of life in the individual. To learn the laws of the union, in one individual and definitive unity, of the infinite dominant and recessive potentialities that must encounter one another in the mysterious labyrinth in which life is prepared—therein lies the greatest problem of the present day.
It is that which should constitute our guiding purpose.