Since, as Weismann[263] admits, interference with the nutrition of the germ plasm will result in the production of variations, the fact is evident that even according to the Weismannian principle the nutrition of the parents will determine the power of the embryo to pass through the various embryonic stages up to the developed child. Impairment of nutrition may check this development at any standpoint, and may thus produce any or all of the defects due to degeneracy. Weismann has no doubt about the inheritance of a "tuberculous habit whose peculiarities are certainly transmissible." Practically, therefore, even according to Weismann, that most emphatic critic of the transmission of hereditary defect, a condition of nervous exhaustion is produced in the parents which may be transmitted as a whole to the offspring, or may simply so affect the ovum as to produce various arrests in development with hypertrophies elsewhere. The influence of nervous prostration in the father may be overcome by conditions in the mother tending to help development. As her share in the germ plasm is most emphatic, not only at the time of the formation, but also during the entire development of the embryo, production of degeneracy will largely depend on her nutrition. The influence of healthy atavism is much more emphatically exerted through the female, albeit even in the male it may overcome the nervous exhaustion of the ancestor so far as reproduction of it is concerned. While many are called, few, owing to healthy atavism, are therefore chosen for complete degeneracy. Although heredity plays a large part in the degeneracy of the individual, still environment in many cases exerts a greater influence in determining, according as it strengthens or weakens healthy atavism, the depth of degeneracy. Treatment, therefore, both of the individual and of the family is largely a question of prophylaxis or prevention.