_Heredity._--To this Charcot used to attach the greatest importance. In every case of tic, he maintained,[31] however trivial, especially if attended with phenomena such as coprolalia, a hereditary element is discernible. Similar heredity is of common occurrence. In Gintrac's cases, two brothers had the same facial tic. Blache's patients were three children in the same family. Delasiauve observed identical tics in brother and sister, and Piedagnel in mother and daughter. A father and two sons of whom Letulle has given an account all suffered from a tic of blinking. The same author has seen two brothers with a complex tic of face, scalp, arms, and diaphragm. More recently Tissié has recorded a series where a mother was affected with ocular tic, while the eldest son also had an ocular tic, which eventually spread to the face and was associated with a spasmodic cough; a younger son was likewise the subject of ocular tic. A case has come under our notice of a young girl with a head-tossing tic which had been preceded by a variety of others now imitated by her youngest sister, such as sniffing, screwing of the face, shaking of the shoulders, abrupt pulling up of the garters, etc. These and similar instances undoubtedly serve to show the effect of hereditary predisposition; but the element of imitation enters no less into the question, and the elimination of its influence, owing to family promiscuousness, is peculiarly arduous. To this point we shall revert immediately. Dissimilar heredity, in any of its forms, neuropathic or psychopathic, is no less frequently met with, and emphasises the kinship of tic with almost all the psychoses and neuroses. It is a matter of common observation for a _tiqueur's_ father to be a neuropath, his mother a hysteric, his brother an epileptic, or his grandfather a general paralytic or a maniac, while neurasthenia, hypochondriasis, psychasthenia, etc., or organic disease of the nervous system, may occur among the collaterals. A case has been under our care of a boy M., who has two brothers and one sister, all in good health. The sister bites her nails. The mother is normal, but excessively weak where her children are concerned. The father is neurasthenic, and the grandfather has trigeminal neuralgia. Occasionally a family history of syphilis or alcoholism is forthcoming. Sometimes tic and psychical troubles alternate. Flatau[32] quotes a case of a mother with impulsions and a son with tics, and another of a mother and sister who tic, with a son possessed of fixed ideas.