BOWMAN LECTURE. 



LXT 



although not manifestly colour-blind, both carry the 

 defect (Fig. 1, II). If one of these two grandmothers of 

 the male IV, 1 is free from taint (as in II, Figs. 2 and 3), 

 it is impossible to understand that she can have any more 

 influence than if she came from a different stock; and the 

 same will be true if one or both of the two grand- 

 parents (parents of the cousins) be male and unaffected 

 (II, Figs. 4 and 5). 



In this connection Fig. 48 (Leber's disease, a sex- 

 limited affection; Klopfer's case, 1898), is instructive. 



f Comsin-Mavriafte in Sen-limited Disease. 

 Fi<j. I Ffy 2. _ Fifl. 3 ^ Fij. 4 Fi. S 



r 



ying 



Disease 



The disease appeared only in the last two of the eight or 

 nine known generations, in three childships cousins to 

 each other, and, according to rule, affected males only."* 



Each of these childships was the issue of a con- 

 sanguineous marriage ; but, as the lines show, these 

 parental cousinships all came from grandfathers who were 

 unaffected, and therefore, on the hypothesis, did not 

 contain the disease. If the normal rule obtained, as 

 seems to have been the case, the disease must have 

 followed the thick, black line to an affected male 

 * Some particulars of this pedigree will be found at p. cvm. 



