4 Eugenics Rkcord Office, Bui,i.etin No. 4 



Practically, it is not always easy to distinguish the simplex 

 from the duplex conditions, although frequently the simplex con- 

 dition is indicated by an intermediate mental status. We may, 

 however, construct six main tables, subsequently dividing the 

 second into two parts, according as closely as possible with the 

 probabilities in respect to germinal composition of the parents. 



4. Results. 



In Table I there is only one mating with both parents epileptic 

 (Fig. i). There were three children of this mating about whose 



^-ttti 



Fig. 



I. Chart showing, at the bottom, the offspring of two epileptic 

 parents. In this case both parents are likewise feeble-minded. Of the 

 four children three are epileptic and No. 4 who died before he was four- 

 teen was feeble-minded. Case 3669. 



condition something is known; all were epileptic. There were 

 five matings (see Figs. 4, 5, 6, 7) in which one parent was 

 epileptic and the other feeble-minded ; of the 14 offspring there- 

 from, 8 were epileptic and 6 feeble-minded. There were 6 mat- 

 ings of 2 feeble-minded parents (Figs. 8, 9, 29) ; and they yielded 

 21 known offspring. Of these 16 were feeble-minded and 5 were 

 epileptic. It appears, consequently, that when both parents are 

 epileptic, both feeble-minded, or one epileptic and the other feeble- 

 minded all of the offspring will be either epileptic or feeble- 

 minded, and the proportion of epileptics in any fraternity in- 

 creases with that in the parentage. The rule that two feeble- 

 minded parents have only offspring like themselves was appar- 

 rently first noted by one of us in 1909. The extensive and valu- 

 able data of Goddard (1910) offer several matings that accord 

 with this rule. Through the kindness of Dr. Goddard we have 



