THE HEREDITY OF EPILEPSY ANALYZED BY THE 



MENDELIAN METHOD. 



By DAVID FAIRCHILD WEEKS, M.D. 

 (Read April ig, igi2.) 



Until recently it has been considered sufficient to determine the 

 known number of epileptic ancestors or other relatives of a case of 

 epilepsy, and then take this proportion as the index of heredity, with 

 the natural result that the index increased as the study of the family 

 was extended, resulting in a difference of from 20 to 75 per cent., 

 as determined by dift'erent workers. 



In our study of the inheritance of epilepsy at Skillman, we are 

 endeavoring to analyze our data by the Mendelian method, which 

 assumes that the inheritance of any character is not from the par- 

 ents, grandparents, etc., but from the germ plasm out of which every 

 fraternity and its parents and other relatives have arisen. 



The relation of soma (body) and germ plasm is as follows: 



1. If the body possesses a trait of the recessive to normality sort, 

 it lacks the unit character upon which normal development depends, 

 and it is prima facie evidence that the representative of that char- 

 acter is absent from its germ plasm, consequently such a person can- 

 not transmit the character in question. The condition in the case 

 when the determiner is absent may be called nulliplex. 



2. If the body possesses a trait of the dominant to normality 

 sort, it is evidence that the germ plasm has the corresponding de- 

 terminer. But either one of two conditions is possible, (a) The 

 determiner was derived from both parents, so that it is double in 

 the germ plasm, and all the germ cells have the determiner ; or else, 

 {b) it came from one parent only, in which case it is single in the 

 germ plasm, or simplex, and half of the germ cells have the deter- 

 miner and half lack the determiner. 



A moment's consideration will show that three kinds of somatic 



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