If the son becomes a toper, therefore, it is because he, like his father before him, was born with a defect--weak control--which might have made of him a drug-fiend, a tobacco-slave, a rake, or a criminal; in his home drink would naturally be the temptation nearest to hand, and he would show his lack of control in drunkenness. The way a lily-seed is treated makes a vast difference to the plant which arises. If sown in poor soil, and neglected, a dwarf, sickly plant will result; if sown in rich soil, and given every care that enthusiasm, money and skill can suggest or procure, the result will be magnificent. So with man. A well-nourished mother, free from care and disease, may have a finer child than a half-starved woman, crushed by worry and work, but neither starvation nor nourishment alter the inborn character of the child. The _body-cells_ are greatly changed by disease, poison, injury, and overwork, but these changes are not passed on, and despite the influence of disease from time immemorial, the _germ-cell_ produces the same man as in ancient days. Without this fixity of character, this "continuity of the germ-plasm", "man" would cease to be, for the descendants of changeable cells would be of infinite variety, having fixity of neither form nor character. Epilepsy, hysteria and neurasthenia are all outward signs of defect in the germ-plasm, and so they (or a predisposition to them) can be passed on, and inherited. If a man shows a certain character, his plasm, had, and has, the causative factor. He may have received it from _both_ his parents, when it will be _strong_, or from one only, when it will be _normal_. If he have it not, it is absent. The same applies to the plasm of the woman he mates, so there are six possible combinations, with results according to "Mendel's Law." _All_ the children will not inherit a taint unless _both_ parents possess it, but, however strong one parent be, if the other is tainted, _none_ of the children can be absolutely clean, but will show the taint, weak, strong, or dormant. This means that neuropathy will recur--and that it has previously occurred--in the same family, unless there be continual mating into sound stocks. If there is continual mating into bad stocks, it will recur frequently and in severe forms. All intermediate stages may occur, depending entirely on the qualities of the combining stocks. From this we shall expect, in the same stock, signs of neuropathic taint other than the three diseases dealt with here, and these we get; for alcoholism, criminality, chorea, deformities, insanity and other brain diseases, are not infrequent among the relatives of a neuropath, showing that the family germ-plasm is unsound.