Still more important must be considered the objections of empirical science, which up to this time was completely convinced of the heredity of acquired qualities. Popular experience, as well as that of physicians, universally speaks of inherited disease-germs, and in certain cases, particularly in mental diseases, physicians are so thoroughly convinced of their inheritability that the first question put to the relatives of such sufferers usually is whether the disease has ever appeared in the parents or family of the patient. This fact is so deeply grounded in the general belief, that the modern naturalistic school of novelists, the school of Zola, Ibsen, and their associates, are wont to devote their main efforts to the problem of inherited evils. Now the inheritability of certain evil conditions, even though proved, would not by any means be an absolute disproof of Weismann’s theory; for, inclined as much as we may be to derive diseases from mistakes and sins against a natural mode of life, such as colds, drunkenness, dissipation, mental and bodily over-exertion, we yet cannot deny _a priori_ that blastogenic diseases, or diseases originating in the germ-plasm, may exist, which without any doubt would then be transmissible. It also does not lie beyond the realms of possibility that congenital malformations, such as hare-lips, supernumerary fingers, and the defects which show a remarkable disposition to heredity, fall into this category. These blastogenic germs of disease would then, of course, have to be distinguished from the somatogenic diseases (or the diseases produced in the body by external causes), which never could be inherited.