PRELIMINARY REPORT OF A STUDY OF HEREDITY 



IN INSANITY IN THE LIGHT OF THE 



MENDELIAN LAWS 



By Gertrude L. Cannon, A.M., and A. J. Rosanoff, M.D. 



KINGS PARK STATE HOSPITAL, NEW YOItK 



Insane hospital statistics show plainly that heredity has much 

 to do with the causation of certain forms of nervous and mental 

 disease. Yet we know but little of the exact conditions under 

 which such disease is transmitted from parent to offspring. The 

 object of the present research has been to accumulate and examine 

 such data as may serve to throw some light upon this obscure 

 problem. 



It has been shown that the laws governing the transmission of 

 traits by heredity, as established by Mendel, hold good not only 

 for plants and the lower animals, but also for man, at least as 

 regards certain characters, such as color of hair and color of eyes. 

 In view of this fact our problem has assumed for us a more defi- 

 nite form. It is simply: Are any of the forms of nervous and 

 mental disease transmitted from generation to generation in ac- 

 cordance with the Mendelian laws? 



§ J. The Mendelian Laws. — Perhaps a brief review of the 

 essential points of the Mendelian laws will not be superfluous. 



The total inheritance of an individual from his parents is 

 divisible into unit characters, each of which is inherited inde- 

 pendently of all the rest and may therefore be studied without 

 reference to other characters. 



The inheritance of any such character is believed to be depen- 

 dent upon the presence in the germ plasm of a unit of substance 

 called a determiner. 



With reference to any given character the condition in an 

 individual may be dominant or recessive: the character is domi- 

 nant when, depending upon the presence of its determiner in the 

 germ plasm, it is plainly manifest; and it is recessive when, owing 

 to the lack of its determiner in the germ plasm, it is not present 

 in the individual under consideration. 



