VOL. XXXII.] PHILOSOPHICAL TRANSACTIONS. - 603 



pellicle within it, but discovered a small yellowish body at the bottom of the 

 bulb of the eye, of a lenticular shape, without adhesion to any of the other 

 parts, which appeared to be the crystalline humour, become opaque, and rather 

 less than its natural size, having two or three small dents, or impressions, made 

 in its circumference, which it had received from the needle during the opera- 

 tion of couching. 



The next day he examined the right eye in the same manner, in the pre- 

 sence of several eminent physicians and surgeons, and found in it the crystalline 

 become opaque, and depressed in the same manner as the former, to the bottom 

 of the eye, still bearing the marks of the needle evidently on it, but could find 

 no pellicle within the eye. S. Benevoli further relates, that having formerly 

 made some experiments on the eyes of dead subjects, at Bologna, in company 

 with Dr. Valsalva, he had introduced the needle into the eye in the same place, 

 and in the same manner, as is commonly practised in the operation of couch- 

 ing, and having afterwards dissected the same eyes, he had always found that 

 the needle had passed into the eye on the backside of the crystalline humour, ' 

 so that it had been impossible to bring the needle forward from thence into 

 that part of the aqueous humour, which is seated between the uvea and the 

 crystalline humour, in order to depress a pellicle seated there, according to the 

 common opinion, unless he would have passed his needle through the body of 

 the crystalline. 



This curious author likewise observes, that the aforesaid space, between the 

 uvea and the crystalline humour, is so very narrow, that though he finds it 

 not impossible to introduce a needle into that space, yet there is by no means 

 room enough to turn the needle up and down in all directions, with the 

 freedom used in couching cataracts, without wounding either the uvea, or the 

 crystalline. 



Lastly, S. Benevoli observes, that in his practice of couching cataracts for 

 many years, having generally couched about 12 or 14 in a year, he had always 

 found, that he worked on a hard and resisting substance, which being tenderly 

 touched by the needle, would vibrate and fluctuate backwards and forwards, 

 and would sometimes return against the needle with a sensible impetus, which 

 by no means agrees with the common notion of the cataract's consisting in a 

 pellicle or membranous substance. 



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