process of their extinction might be initiated by an artificial sterility. Such a measure would be impracticable, because it would be impossible to fix a limit; and it would certainly be inefficacious in proportion as the temperaments of the persons concerned should be averse to their submission to the laws. The contest may be made by less uncertain processes.
Restoration of a degenerated race—return to mediocrity, as it has been called—may be effected through crossing with individuals of healthy races. M. Sanson has shown, by good examples drawn from zoötechny, that heredity of biological characteristics, and even perhaps of the sex, is generally influenced by the condition of nutrition of the progenitors. The stronger of them attracts the resemblance to his side. It may be assumed that in a union including a morbid factor the healthy factor is in the better position to prevail, and all the more so because it has the atavistic tendency of the other side in its favor. But whether because of the rarity in our time of absolutely healthy elements, or for some other reason, we usually find that, in crossing, the good are more likely to lose than the bad to improve.
There are still other means than happy crossing that may help in the return to mediocrity. Less and less deficient children may be observed to be born in a family of degenerates as the biological conditions of the parents improve. There is nothing surprising in the fact that disorders of nutrition have an injurious influence; all improvements of nutrition may, on the other hand, be accompanied by a correlative amelioration of the products. Generation is, as a whole, the resultant of an excess of nutrition; the lower organisms, absorbing in the medium in which they live more elements than they need for the repair of their losses, increase in volume. When this increase exceeds a certain limit, the individual breaks itself up to form new beings. The process is much more complex in the higher animals, but it is fundamentally the same; and Haeckel has felt free to call reproduction the excrescence of the individual. The best conditions for generation are the best conditions of nutrition. To the regularity of their nutrition is due the regularity of the folding of blastodermic leaflets and the regularity of their further evolution. The arrest of development of a single cell in the earlier periods of evolution is susceptible of determining grave deformations.
Facts observed in human families, in which we see degenerates producing offspring less and less deficient as their own conditions of nutrition improve, indicate that under the influence of a superactivity of nutrition defective organisms might furnish a normal epigenesis. Further, the possibility of combating during the embryonary period the degenerative tendency which is
