LESS IMPORTANT HEREDITARY AFFECTIONS. 309 



females, all the females escaped, while eight of the 

 nine sons were colour-blind. 



CATARACT. This is another diseased condition of 

 the eye which is distinctly hereditary. Like colour- 

 blindness, it is much more frequently met with in 

 males than in females, but, unlike colour-blindness, it 

 is intimately related with another degenerate condi- 

 tion, viz., the neurotic diathesis. 



This imperfection, which consists of degenerative 

 changes in the tissues of the lens of the eye, causing 

 opacity and consequent blindness, is in the usual 

 course of nature a senile change : but just as we find 

 earthy degeneration in the tissues of the youthful 

 criminal, so in some degenerate families we find 

 cataract in childhood, infancy, and even at birth. 

 This degenerate condition of the eye is very common 

 in neurotic families, and also in those of the scrofu- 

 lous and rheumatic diatheses. It is a common char- 

 acter in the idiot, the imbecile, and the epileptic ; so 

 common indeed is it in this class that its presence at 

 once attracts the attention of all observant visitors to 

 our idiot asylums. It is also common among the deaf 

 and dumb and their relatives. 



As I have said, it appears much more frequently 

 in the male members of the family than the female, 

 but it is regularly transmitted through the unaffected 

 females to their offspring. This is well shown in the 

 following family tree, in which Dr. Appenzeller follows 

 the blight through four generations : 



