BOWMAN LECTURE. 



CX IX 



it*; here,, therefore, the cousinship does not increase the 

 risk to the children. Next, if the cousinship comes 

 through the wife's unaffected father she will not, any 

 more than her unaffected husband, contain the disease, 

 and might have been unrelated so far as risk of this 

 particular disease is concerned. The only case in which 

 a cousin marriage increases the risk is when the man is 

 affected with the disease and his cousin wife carries it 

 latent, deriving it either from her affected father or 

 through her mother from an affected male of an earlier 

 generation. 



The differential diagnosis of Leber's disease, generally 



Fiq.So 



II 



easy, may now and then be difficult when we have to 

 distinguish it from familial optic atrophy associated with 

 tower-skull and other cranial deformities. t I have pro- 

 visionally included the cases by Eampoldi and Suckling, 

 which, although probably genuine, presented some unusual 

 features and are not described in sufficient detail ; and one 

 of Higgeiis's cases is also included, although the author 

 seems inclined to think that syphilis in the mother may 

 have taken a share in causing the optic atrophy that 



* But compare the suggestion on last page as to the possible influence 

 of diabetes or other agencies in exciting a latent tendency to the disease. 



f Patry, " Contribution a Fetude des Lesions Oculaires dans les Mal- 

 formations Craniemes/' These de Paris, 1904. Several cases of tower-skull 

 or oxyeephaly will be found in the T.O S. and elsewhere in British 

 literature. 



