BOWMAN LECTURE. 



cm 



we suppose, and how that attention has been drawn to it 

 we may hope soon to hear of more cases. There has 

 been no opportunity for anatomical examination, and 

 nothing is known of the intimate nature of the night- 

 blindness ; we cannot even be sure whether its seat is 

 retinal or cerebral. 



In the other group of hereditary night-blindness shown 

 in Figs. 42, 43, and 44 (Appendix V), the leading features 

 are limitation to males with descent through normal-sighted 

 females and myopic refraction, but visual acuity with cor- 



rection often subnormal. Slight changes are sometimes 

 found at the fundus, but even when present they are not 

 constant either in character or situation. Considerable 

 myopia has certainly been present in childhood in some of 

 them, and perhaps in all; 3'5 D. to 9 D. are the usual 

 figures, 11 D. the maximum recorded. No case has been 

 found with steadily progressive myopia or severe myopic 

 changes at the fundus. Colour-vision was normal in such 

 as were tested. Nystagmus has been noticed in a few. 

 Nothing is known of the nature of this condition; but the 

 association of early myopia, frequently defective central 



