(2) Investigations, like that of the Jukes family by Dr. Dugdale, have established the fact that criminals, paupers, imbeciles, drunkards, prostitutes, and other degenerates frequently spring from the same family stock. A very large percentage of the prisoners in our prisons have come from more or less degenerate family stocks. (3) Criminals more often show other forms of degeneracy than criminality than does the average population; that is, criminals often belong to one of the well-recognized degenerate classes, such as imbeciles, epileptics, and insane. These three arguments may be considered to be conclusive proof that criminality is in some cases a manifestation of physiological degeneracy; but they do not show that the bulk of criminals come from physiologically degenerate stocks. On the contrary it is highly probable that the marks of physiological degeneracy are not to be seen in from more than 25 to 30 per cent of our criminal class. These marks of degeneracy are of course especially common among the instinctive or born criminals, and to some extent they are found among the habitual criminals also. _The Influence of Heredity on Crime_. A word must be said about the influence of heredity on crime. The student will remember that, according to the modern theory of heredity, acquired characters, or characteristics, are not transmissible. Accordingly, when we find crime running in a family for generations, as in the Jukes or Zero families, we must assume either that the criminal tendency is transmitted by the social environment or that it is due to some congenital variation in some ancestor. In other words, if a person is a criminal by hereditary defect, if the criminal tendency is born in him, as it is in the instinctive criminal, he will transmit the tendency toward crime to his offspring; but if a normal person becomes a criminal by acquired habit he will transmit no tendency toward crime to his children, although his children may of course acquire the tendency from their social environment. This is not saying, however, that in such cases as habitual drunkenness and habitual vice an impaired constitution may not be transmitted to offspring. But this, strictly speaking, is not the transmission of any specific acquired characteristic, but only a general transmission of impaired vitality which may show itself in crime and in various forms of degeneracy. The germ cells are of course a part of the body, and anything that profoundly impairs the nutrition of the body generally, such as alcoholism and constitutional diseases, would also impair the nutrition of the germ cells, and result in a weakened constitution in offspring.