Slonaker, Eye of the Mole. 359 



wide area of protoplasm. The average size of the cell is .0074 

 mm. by .0095 mm. I have not been able to demonstrate the 

 processes of these cells. Slight projections of the protoplasm are 

 found in places which indicate that some of these cells are in the 

 process of forming branches. This layer, as in the young at 

 birth, shows the most rudimentary condition of any of the cells 

 of the retina. 



The inner molecular layer is quite variable in thickness. 

 Its uniformity depends on the arrangement of the ganglion cell 

 layer. When these cells are not crowded into a mass the inner 

 molecular layer is quite uniform in thickness (Figs, ii, 12 and 

 13). Frequently, however, the ganglion cells encroach on this 

 layer and we find it of various thicknesses (Figs. 16 and 18). 

 The average thickness of this layer is .0478 mm. 



The ganglion cells have no definite arrangement. In some 

 cases they form a fairly uniform layer (Figs, 11, 12, 13 and 18), 

 in others they are massed, all evidence of a layer having been 

 destroyed (Figs. 14, 19, 24, 25, 26 and 27). In a normal 

 mammalian eye these cells are arranged in one or two irregular 

 rows. But in the mole they are always in more than two rows. 

 The ganglion cells and nerve fibers are so confused in their ar- 

 rangement that at the best they are not distinguished as two 

 layers. They form a combined average thickness of . 1256 mm. 

 Most of the cells have the shape of typical ganglion cells 

 (Fig. 31)- They possess two or more dendritic processes 

 (Fig. 31, d), which can be followed some distance from their 

 origin. Owing to the fact that they took the stain poorly I 

 was unable to follow them far from the cell. A single axone 

 is given off from each of these typical cells. It can be traced 

 in almost a direct course to the center of the retina where it 

 joins with others to form the optic nerve. In regard to the rel- 

 ative position of the ganglion cells and the course of the axones 

 the mole presents a marked contrast to the normal arrange- 

 ment. The ganglion cells are not always oriented so that the 

 dendrites can go directly toward the inner molecular layer and 

 the axone toward the inner surface of the retina as found in the 

 norrtial eye. The orientation is frequently such that the den- 



