398 CHIKANOSUKE OGAWA 



Between the pigment-free cells of the inner layer, occasionally a 

 few rounds cells can be seen, which are larger than the iris epi- 

 thelial cells and richly laden with pigment granules. It is diffi- 

 cult to decide whether they are leucocytes or modified epithelial 

 cells, though the former assumption seems more likely. The 

 upper iris, thus depigmented, elongates at the same time down- 

 ward. 



The upper iris edge becomes more enlarged by the increase 

 of cell height as well as by the widening of the split, and thus 

 forms a round vesicle. Mitosis is often seen here. The part 

 which connects the enlarged iris edge with the original iris — the 

 stalk — becomes gradually thinner and the split between the two 

 layers here diminishes, so that the cavity of the iris edge does not 

 communicate with the original split of the iris. Then the cells in 

 the posterior pole of the vesicle grow higher and at the same time 

 thinner in a radial direction. The adjoining cells also become 

 successively high. In short, the cells in the posterior wall take 

 up a concentric arrangement and protrude into the cavity of the 

 vesicle. These are lens fibers. As the development proceeds, 

 the cavity is narrowed by these lens fibers and finally disappears. 

 Here a solid lens is formed, which is still connected by the stalk 

 with the original iris. The cells constituting the stalk are flat 

 or cuboidal and often small. 



When the lens grows and attains a pretty advanced stage, 

 pigmentation comes back gradually to the iris epithelium and 

 the thickening also decreases. In this way the normal state is 

 restored. Sometimes the pigmentation process in the iris epi- 

 thelium is retarded, though the thickness returns to the norm or 

 vice versa. The lens separates from the iris and remains in the 

 pupillar region. The lens may either simply separate from it or, 

 prior to separation, be connected with it by fibrous ligament. No 

 consideration is given at present to the question as to how this 

 ligament was formed. On the other hand, the lens may or may 

 not become connected with the lower iris until it separates from 

 the upper iris. This connection occurs directly or by fibrous 

 ligament. The epithelium of the lens is sometimes pulled out 

 where the lens is in connection with the iris, namely, about in the 



