As a final illustration of a serious malady in man which acts as a dominant in inheritance, let us take _Huntington's chorea_. Ordinary _chorea_, or St. Vitus' dance, a disorder characterized by involuntary muscular movements, is commonly though not always confined to children and usually ends in recovery, but _Huntington's chorea_ appears typically in middle life and is a much more dangerous malady. Fig. 26, p. 114, represents the family history of one of five cases which have been studied by Doctor Lorenz in the Mendota Hospital for the Insane. All charts which have been platted of this malady show it to be inherited as a dominant. This means that half of the children of an individual who carried the malady in the simplex condition, and all the children of one who carries it in the duplex condition, are probably marked for this terrible end. And the true horror of it can only be appreciated by one who has seen the last stages of the malady. The victim once in its grasp gradually becomes wrecked in mind and body; the muscular twitchings and disorders of movement continually increase and dementia progresses until at last death ensues. Fig. 27, p. 115, is another chart showing inheritance of _Huntington's chorea_. In still a third case at the Mendota Hospital, the gravity of the situation can be appreciated when one realizes that the patient is the father of ten children, ranging in age from one to seventeen and one-half years. The calamitous fact that this disease does not manifest itself usually until middle life makes it likely that these children will all reach maturity, marry and in turn probably produce offspring before the doomed members of the family realize their fate. [Illustration: FIG. 26 Chart showing descent of _Huntington's chorea_ in the P---- family (courtesy of Dr. W. F. Lorenz). Squares represent male, circles female; shaded figures are choreic members of the family; partially shaded figures, slightly affected or very "nervous" members. The members of the last generation are for the most part still too young to show their condition. The cross indicates the individual in the asylum from whom the record was traced back.] CASES OF RECESSIVENESS IN MAN