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Witli high magnifying powers no indications of structure 

 are discernible in it, except faint marks of lamination in the 

 stout capsules of the largest mammalia. The front half of 

 the capsule, or, more exactly, that part of it which lies in 

 front of the attachment of the suspensory ligament, is thicker 

 than the posterior half; at a rough estimate, its thickness may 

 be taken to be three times as great. 



This difference, and the unavoidable implication of the 

 front half of the capsule in operations for the removal of 

 cataract, have led to the adoption of the terms anterior and 

 posterior capsule. As these terms are convenient, their use 

 is not objectionable, if it be borne in mind that they refer to 

 two halves of one and the same size, and not to two distinct 

 ones. Besides being stouter, the front half of the capsule 

 differs from the posterior in being lined with an epithelium. 

 This consists, in the central region, of a single layer of large, 

 flat, polyhedral cells, each enclosing a circular nucleus. 

 These nuclei are remarkably uniform in size and shape. At 

 the edge of the lens the epithelial cells are much smaller, and 

 so closely crowded that their nuclei are separated by very 

 small interspaces. In mature lenses the marginal epithelium 

 is composed only of a single layer of cells ; but in young and 

 growing lenses it is formed of several layers of cells with an 

 imbricated arrangement, which constitute the matrix out of 

 which the fibrous tissue of the lens is evolved. The capsular 

 epithelium plays an important role in the production of the 

 so-called capsular opacities accompanying various forms of 

 cataract, congenital as well as acquired, for out of it are 

 evolved, by what may be called a perverted development, 

 nucleated fibrous webs, often of great toughness and density, 

 underlying the inner surface of the capsule. It must not be 

 forgotten that the capsule itself never becomes opaque, what 

 are called opacities of the capsule being always deposits of 

 opaque substances, or adventitious growths upon its surfaces. 

 These may exceptionally be overlaid by a transparent colloid 

 substance, and their own opacity may seem to be seated in 

 the capsule ; but the colloid mass is not a part of the capsule 

 — it is something superadded to it. I am aware that some 

 good observers deny this origin of these intra-capsular fibrous 

 webs, which are not optically distinguishable from a con- 

 nective substance. They ask — How can a connective sub- 

 stance be the derivative of an epithelium ? And they maintain 

 that in all these cases the capsule has not been entire, but it 

 has had some rent through which these fibrous webs have 

 intruded themselves from Avithout. I cannot yield to this 

 opinion, because I have found such webs on the inner surface 



