=Gout.--=In such disorders as gout there is little question but that a tendency to it runs in families. On the other hand it may also be acquired without special susceptibility. There is no evidence, however, that because a father has gout the effect of the gout is reflected on his germ-cells and the son has gout as a result. Indeed, often a son who becomes gouty was born long before the father became gouty. Son and father both have gout then, because each has innate germinal tendencies which when subjected to certain evocative stimuli become expressed as gout. =Nervous and Mental Diseases.--=Inasmuch as the question of nervous and mental diseases has become one of such overshadowing importance at the present day, a discussion of the subject at some length will be presented in a separate chapter. I shall merely point out here that the general verdict of experts in nervous and mental disorders is to the effect that externally induced mental disorders are of rare occurrence except as the result of general poisoning or enfeeblement of the system in some way, or by traumatic conditions such as a blow on the head, and that there is no evidence of the transmission of the effects of such conditions. In most cases of insanity, supposedly caused by fright or worry, a close study of the family stock will reveal nervous instability of some kind. The supposed cause has been merely the precipitating stimulus which has brought to expression a dormant weakness of germinal origin. The stress and strain of modern life is particularly likely to test out and reveal such neurally unstable individuals. =Other Disorders Which Have Hereditary Aspects.--=Space will not permit discussion of various other specific disorders which are known to have important hereditary aspects, although none shows any convincing evidence of having become hereditary in nature through first affecting the soma. Some of these, such as epilepsy and other nervous affections, tuberculosis, color-blindness, cataract and various malformations, have already been mentioned. Others that may be listed are cancer, arterio-sclerosis, obesity and certain forms of rheumatism, and of heart and kidney diseases. In practically all of these cases in which heredity enters as a factor the condition is one of inheriting a special susceptibility and not the disease itself. Which means simply that the disorder in question is much more easily called forth in such persons by appropriate bacterial or other stimulus, than in the case of the normal individual.