of the Capsule of the Crystalline Lens and Ciliary Zone, 13 



line lens to polarized light, he found it depolarize four faint 

 sectors of light considerably below the white of the first order; 

 "thus indicating a positive doubly refracting structure, like 

 a sphere of glass rapidly cooled, and increasing in density 

 towards the centre." 



2nd. The celebrated Cuvier, in his Lectures on Compara- 

 tive Anatomy, mentions as a general fact that the nucleus is 

 hardest in those lenses that are most convex. My own ob- 

 servations on the lenses of quadrupeds, birds and fishes, con- 

 firm this fact in its fullest extent. The greatest hardness of the 

 nucleus of the ox is not greater than the hardness of the lens 

 of the cod half way between the surface and the centre ; and 

 very flat lenses, such as those of fowls in general, are scarcely 

 more dense at the centre than those of the cod very near the 

 surface. These appearances are in strict accordance with the 

 theory; but surely they do not correspond with those which 

 might be expected if the lens were a solid organized for the 

 express purpose of correcting the spherical aberratiri of light. 

 The fact I have stated above, that I had found thr /ery young 

 foetal lens entirely fluid, and of the same refractive power as 

 the soft or fluid external part of the maternal lens, together 

 with the universally soft state of young lenses, — strongly im- 

 press on my mind a conviction that the substance of the lens 

 is a secretion of a peculiar fluid ; and what has been termed 

 the liquor Morgagni is probably this fluid recently secreted. 

 This impression is greatly strengthened by the account of ex- 

 periments made by Messieurs Cocteau and Le Roy d'Etiolle, 

 and published in the Journal de Physiologie for January 1827. 

 These gentlemen performed the operation of extraction on 

 many rabbits, cats, and dogs ; and they found that in most in- 

 stances, though not in all, the capsule, examined at the end of 

 four or six weeks, contained a new body, of a lenticular form, 

 and approaching in consistence to that of the extracted lens. 

 In one of these experiments they allowed the animal, a rabbit, 

 to live six months after the operation. " The crystalline cap- 

 sules were then found perfectly transparent without a visible 

 cicatrix; and they contained each a lens of the same volume 

 and consistence as those extracted. For the sake of greater 

 certainty, they were immersed in hot water, when they became 

 opake, hard and friable like ordinary lenses ; the sole differ- 

 ence being, that the disposition in brilliant plates was evident 

 only on the outer layers." This fact shows the importance of 

 preserving the capsule in the operation for cataract when it is 

 not diseased, and completely disarms any objection that may 

 be urged against our theory from some individuals having been 



