BOWMAN LECTURE. LXXXI 



thus if a lamellar opacity measures 6 mm. across, the lens 

 must have had at least that diameter, or a little more, say 

 7 mm., before the opacity formed, and in such a case we 

 should probably be right in concluding that the cataract 

 developed shortly after birth.* Now the largest lamellar 

 opacity that has been measured after extraction of the 

 lens had a diameter of 6 mm. ; the ordinary size is from 5 

 to 5*5 mm. In some it is much less, down to, say, 3'5 and 

 4 mm., and in these cases of small-sized opacity we should 

 be justified in assuming that the morbid process had 

 begun and ended before birth, even if there were no 

 clinical evidence to that effect. There is, however, enough 

 of such evidence to be convincing. We have first the 

 observation attributed by Hulkef to Bowman about the 

 year 1846, of lamellar cataract found in a kitten a few 

 days old. Of later observations Hosch in 1397 pub- 

 lished a case in which a mother had seen cataract in her 

 baby's eyes at its birth, the diagnosis of lamellar being 

 made by Professor Horner when the child was six weeks 

 old and the opacity measuring 4 mm. across at the 

 age of six years. The same woman detected the opacity 

 in another of her children two days after birth. J Mr. 

 Fisher has given me the case of a female baby (Fig. 14 ; 

 IV, 2), in whom he diagnosed dense lamellar cataract at 



* Collins, however, concludes that the opacity must always be ante- 

 natal if the part affected is, as is assumed, the most peripheral layer ; or 

 that if post-natal the part affected is not the most peripheral. 



f Hulke (T.O.S., vii, 1887, p. 27), defending in his Bowman Lecture 

 (in 1886) the pre-natal formation of lamellar cataract, writes as follows : 

 . . . " the first distinct recognition of lamellar and zonular cataract 

 based on dissection was, so far as I know, made by Mr. Bowman, the 

 subject being a kitten, killed and prepared for lecture in the physio- 

 logical laboratory in King's College. The date of this was, so far as 

 my recollection serves me, 1846, but it might have been slightly 

 later." Mr. Hulke, who, as he tells us in another part of the same 

 Address, was about this time one of Mr. Bowman's dressers, states that 

 he (Hulke) wrote down at the time a description of the appearances 

 although he was unable to find it at the date of the above occasion 1886. 

 The kitten was only a few days old. 



Quoted a? Case 69 in my paper upon "Heredity in Cataract," Jf.L.O.H., 

 xvi, p. 229. 



