EXAMINATION BY OPHTHALMOSCOPE. 565 



cases tliis is sufficient to bring an opacity of the lens distinctly 

 into view, a cataract looking like a dark or black spot in the 

 illuminated eye ; but should this not prove sufficient, the eye 

 may be magnified by the lens which accompanies the ophthal- 

 moscope, and the examiner can limit his vision to the eye by 

 looking through the small aperture at the back of the instru- 

 ment. 



It may here be mentioned that the small instruments made 

 use of by oculists are the best ; the larger ones made by 

 veterinary instrument makers are not nearly so good, and are 

 apt to deceive. 



