352 Journal of Comparative Neurology. 



The size of the lens also varies as greatly as does its 

 shape. With the exception of Figures i6 and 17, the sections 

 of the whole eye represented on Plates XIX and XX pass in 

 each case through the center of the lens. From these figures 

 one can readily see that the lens varies in size from almost 

 none as shown in Figs, 9, 18, 23, 24 and 25 to the very large 

 lens represented in Fig. 26. The most degenerate condition 

 which I have found is shown in Fig. 24. In this case it has 

 almost disappeared. 



The cell structure of the lens presents the same character- 

 istic as described for the young. The cells are irregular in 

 shape and possess no constant form (Fig. 29). A well defined 

 nucleus and nucleolus are usually distinguished. One also fre- 

 quently finds vacuoles of various sizes and shapes in the cell 

 bodies. The cells lack any definite arrangement and seem to 

 fit into each other in a very irregular manner. The concentric 

 arrangement found in a normal lens is wholly wanting. Judg- 

 ing from the shape and the character and arrangement of the 

 cells, one can safely predict that the lens is no longer capable 

 of functioning in a normal manner. Light passing through it 

 would appear as though coming through ground glass. 



When this lens is compared with that of the European 

 mole, a very wide difference is noticed. The American mole 

 lens is much more degenerate. Ritter (5) says that in all the 

 sections of the European mole which he has examined the lens 

 shows the same characteristic form. He further says that the 

 capsule of the normal lens and the mole lens is the same, the 

 cells the same, the same fiber formation is present and the 

 chemical structure is in all its parts the same as that of a nor- 

 mal lens. He also finds in the development of the frog lens a 

 stage in which it offers some similarity to that of the mole. It 

 is the time just before the nuclear formation when it presents a 

 very marked form. "The epithelium of the anterior capsule is 

 a massive one-celled epithelium, the mass of the lens consists 

 of a neat figure of five or six rows of cells, if one simply 

 wishes to judge from the above nuclei. But although the lens 

 nucleus is still absent the legality is already shown in every 



