from natural selection and the non-controllable determinate variation, the most important factor in evolution. Since characteristics resulting from outside forces can be inherited in cases where the germ plasm itself is affected, it follows that much can be accomplished eugenically by public action with a view to environmental improvement. It is quite probable, for example, that exposure to cold, underfeeding and impure air may cause inheritable defects, judging from the before-mentioned experiments of Professor Tower on potato-beetles and the observations of Bezzola.
The seriousness of the environmental influence, furthermore, arises largely from the fact that it is not confined to one generation, but may, after once becoming established in the germ plasm of an individual, be transmitted to many generations by the ordinary processes of heredity.
As it is precisely upon combating such evils as these causes of germ deterioration that the social reformers place their emphasis, we have here an opportunity for the eugenicist to lend his support to those who would improve the race by modifying its environment for the better. While we can not trace accurately the germinal effects of the windowless tenement, the unventilated street-car and the factory where women work a]l day in poisonous fumes, yet the indications are sufficient to range the eugenicist on the side of those who demand pure air by building and factory laws.
Excessive fatigue as a probable cause of defective offspring brings us again into the domain of labor legislation, for children stunting themselves in factories and railroad men compelled to run their trains for an excessive number of hours are merely glaring instances of what may prove a most spendthrift drain upon the future in the interest of our breathless industrialism.
Since scurvy and rickets by improper food, and gout, rheumatism and Bright's disease brought on by unbalanced indulgence, might both pass on a taint to the offspring, education in hygiene assumes special importance. Our recent pure food legislation, furthermore, is an indication of what enlightened public opinion can do to protect the careless and the ignorant against the evils of malnutrition and improper feeding.
There is definite work for special legislation against certain diseases, such as syphilis, the toxin of which is known to affect the offspring, and the same may be said with regard to the excessive use of opium, cocaine and especially alcohol.
Forel gives startling facts as to the action of alcoholic poison (p. 294, op. cit.):
