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dilated pupil perceptibly contracts. To make this 

 observation successfully, implies frequent practice ;. 

 but this is easily acquired by prevailing on some 

 friend to close his eye tvs^o or three times, and 

 covering it, while closed, with the hand : on rapidly 

 withdrawing the hand, you will notice a contraction 

 of the pupil, as soon as it is exposed to the glare 

 of sudden light. It will materially assist the judg- 

 ment to notice whether the oval outline of the pupil 

 is perfect ; if any irregularity or unevenness is per- 

 ceived, (except as to the upper line, for the reason 

 I already mentioned) — this, though no proof that the 

 optic nerve is diseased, is a certain mark that the 

 organ has received partial injury ; and it is imma- 

 terial to a purchaser from what [cause it has pro- 

 ceeded, if he is satisfied that inj ury has been received. 

 A decided cataract is readily detected, when the 

 nature of the complaint is explained : it is an 

 opacity of the crystalline lens. If the pupil appears 

 to be occupied by any cloudy and whitish sub- 

 stance, I will not say, speaking scientifically, that 

 it is a certain evidence of cataract, but it is pre- 

 sumably to be ascribed to that cause, and at all 

 events it is conclusive as to there being a defect of 

 sight. If the pupil has a circular, instead of a 

 flat, oval shape, already described, this too may be 

 considered as an indication of cataract. 



