This great difference in the estimation of the hereditary influence is due to the personal equation of the statistician, and the care with which other factors are eliminated.

In the more severe form of the hereditary degeneration the same pathological conditions are repeated in the descendants.

In certain cases the severity of the condition increases from generation to generation.

According to Morel there may be merely what is recognized as a nervous temperament often associated with moral depravity and various excesses in the first generation; in the second, severe neuroses, a tendency to apoplexy and alcoholism; in the third, psychic disturbances, suicidal tendencies and intellectual incapacity; and in the fourth, congenital idiocy, malformations and arrests of development.

There are some very definite data with regard to inheritance in the nervous disease known as epilepsy.