I9II] A. J. ROSANOFF AND FLORENCE I. ORR 225 



This is important because it constitutes the criterion which 

 enables us to determine whether any given inherited peculiarity 

 or abnormality is, as compared with the average or normal con- 

 dition, dominant or recessive. /' 



§ 2. Description of Material. 



The total amount of psychiatric material which is available at 

 this hospital is very large. We found, however, that for various 

 reasons, to be spoken of presently, the greater part of the material 

 could not be utilized in our study. 



In selecting cases our aim has been to exclude all those forms 

 of insanity in the causation of which exogenous factors, such as 

 traumata, alcoholism, and syphilis, are known to play an essential 

 part; and we have also systematically excluded psychoses which 

 occur upon a basis of organic cerebral affections, such as tumors, 

 arteriosclerosis, apoplexy, and the like. We are not inclined to 

 dispute the possible influence of heredity in these conditions; we 

 have excluded them merely for the purpose of simplifying our 

 problem by avoiding the necessity of dealing with a complicating 

 factor in the shape of an essential exogenous cause. Moreover 

 there seemed to be reason to believe that the so-called functional 

 psychoses and neuroses are more closely related to each other than 

 to the conditions which we have sought to exclude; and since 

 our material had to be largely massed together for statistical 

 treatment it was important that it should be as homogeneous as 

 possible. 



More than half the patients at this hospital are either them- 

 selves foreign born or the children of foreign-born parents ; and 

 among those who were born in this country of American parents 

 there are many whose homes are in distant states ; thus but a small 

 proportion remained whose families had for two or three genera- 

 tions resided in this country and were accessible to investigation. 



Other difficulties in obtaining our data were due to the ignor- 

 ance of some of our informants or to their reluctance or refusal 

 to co-operate in the investigation ; and in many cases the investi- 

 gation had to be discontinued and the data already collected had 

 to be discarded owing to incompleteness. 



In the actual analysis of the data collected in the course of our 

 investigation the problem in each case was to distinguish, on the 



