LXXXV1II BOWMAN LECTURE. 



characteristic opacities has seemed to me decidedly less 

 in the young than in middle-aged and old subjects, and I 

 am therefore inclined to think that in these people the lens 

 may be clear at birth and for some months afterwards. 

 But few of those affected have had anything done, and 

 not much can be said about the outcome of operations ; 

 but there have certainly been several poor results. In the 

 68 known cases 36, or rather more than half, were females, 

 29 males, the pedigrees containing them showing a total of 

 167 persons males 73, females 75, sex not recorded 19. 

 These numbers are much too small for finality as to sex 

 distribution ; they may easily be upset by fuller data, as 

 may be evident when I say that in one large pedigree 

 (Betts) there were 20 affected males to 1 1 affected 

 females a great excess of males whilst in the other five 

 pedigrees the females were in such large majority that, 

 in the whole six, the male excess was more than neutra- 

 lised, leaving, as just stated, a definite majority of females. 



We find similar examples of extreme difference between 

 one pedigree and another in the proportion of affected 

 males to females in many conditions besides cataract ; 

 precisely as in normal families where the offspring of 

 some parents may be nearly all male, of others female.* 

 No conclusion as to sex incidence of an hereditary disease, 

 except it be a really sex-limited one, is worth anything 

 unless based on very considerable numbers. 



Of other distinct varieties hitherto included under the 

 general title of " congenital cataract " accurate pedigrees 

 will no doubt be forthcoming in. future, and several in- 

 complete ones might be quoted. In the best that I am 

 acquainted with, given by Zirm and Bergmeister under 

 the title "congenital stellate" cataract f (Fig. 17), at 



* Gf. R.L.O.H., xvi, p. 188, for further facts as to sex-incidence in 

 family cataract. 



f Given in R.L.O.H., p. 400, Fig. 54. The four younger generations 

 appear to be completely recorded to date and contain fifteen cases of 

 cataract in about forty persons ; but the sixth generation, consisting of 

 young children, may have increased since. Several other interesting 

 pedigrees of cataract are to be found in the same paper. 



