I. INTRODUCTION. 



In this paper an attempt will be made to analyze the distribution in 

 families of temperament or its expression in mood; and to test the 

 hypothesis that it is dependent upon hereditary factors. 



We recognize a certain average of normal temperament, and that, in 

 many persons, the mood is often associated with an increased activity 

 and elated emotional tone; in others with a decreased activity and 

 lowered emotional tone; while still others pass through alternating 

 cycles of hyperactivity and depression. Let us consider these states 

 in greater detail and seek to define them. 1 



II. DEFINITION. 



1. THE HYPERKINETIC STATE. 



This is an emotional state in which one or more of a series of elements 

 of behavior are shown, of which the following list has been given by 

 Southard (1914, p. 630) : destructiveness, exaltation, homicidal acts and 

 threats, irritability, psycho-motor excitement, and violence. Whether 

 all, or only some, and then which, of these elements shall actually 

 appear in the subject's behavior depends no doubt upon inheritable 

 differences in the nervous mosaic. Now, what the intrinsic cause of 

 hyperkinesis is we do not know, and indeed, we have no ground for 

 assuming that there is any one cause. Southard has pointed out that 

 in nearly every case of reduced optic thalamus the patient has showed 

 hyperkinesis, but it does not follow that this structural peculiarity is 

 always found in cases of hyperkinesis. As Southard says: 



" It is conceivable that somebody will show that simple functions (atrophies, 

 aplasias, agenesias) of the spinal and bulbar gray matter can be correlated with 

 hyperkinesis. Again, somebody may prove that cortical simplifications, 

 either on the impressive or on the expressive side of the apparatus, are corre- 

 lated with hyperkinesis. The fact would probably remain that an entirely 

 normal nervous system i. e., intrinsically normal would also permit hyper- 

 kinesis under various chemical, physical, or other conditions." 



Such other conditions have, indeed, been found, since hyperkinesis 

 is usually associated with reduced blood-pressure. Thus, Dawson 

 (1900) concludes that "the characteristic feature of the general circula- 

 tion in excitement and probably in exaltation is low arterial tension 



x The material upon which this paper is based is that deposited at the Eugenics Record Office 

 founded by Mrs. E. H. Harriman and located at Cold Spring Harbor, Long Island, New York. 

 Many of these data were furnished voluntarily by members of the families concerned. By far 

 the greater part, however, is derived from the reports of specially trained "eugenics field-workers" 

 placed with State institutions through an arrangement for which funds were given by Mr. John D. 

 Rockefeller. Only through the aid of both Mrs. Harriman and Mr. Rockefeller has this study 

 been possible. Mention should be made also of the assistance of Miss Mabel L. Earle, who sup- 

 plied all of the abstracts of the cases on twin inheritance, and of Miss Mary T. Scudder, who 

 prepared the charts and legends and checked all calculations. 



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