Slonaker, Eye of the Mole. 345 



layer. These two nuclear layers here seem to fuse. In other 

 places they are separated by an extremely narrow but well 

 defined outer molecular layer. It appears more like a line 

 than a layer. 



The cells of the inner nuclear layer are much more imma- 

 ture than those just described. They appear as irregular, 

 rounded bodies of various sizes (Fig. 39). The average 

 dimensions are .0039 and .0044 mm. These cells form a 

 continuous layer which is about six cells deep and averages 

 .0292 mm. in thickness. As stated above it is separated 

 from the outer nuclear layer by the very narrow outer mole- 

 cular layer excepting in the region of the lens where the two 

 nuclear layers appear to fuse. I have been unable to find any 

 processes in these cells in the specimens which have been 

 examined. They thus present a much more rudimentary con- 

 dition than the same elements in the European mole. Kohl 

 describes the latter as possessing well defined processes and in 

 general very similar to the condition found in the adult. 



The inner nuclear layer is separated from the ganglion cell 

 by the fairly wide inner molecular layer. This layer is not of 

 uniform thickness. Owing to the very much crowded condi- 

 tion of the ganglion cells these cells may be found variously 

 located throughout the molecular layer. Often the inner 

 nuclear layer and the layer of ganglion cells are in direct con- 

 tact, the inner molecular layer having been pushed aside. 



The position and arrangement of the ganglion cells are 

 quite varied. At times they will form a layer several cells 

 deep, then again they will be crowded into a mass. In no case 

 have I found them arranged in the manner found in the normal 

 mammalian eye. They show a marked degree of development. 

 All the ganglion cells possess a distinct nucleus and well defined 

 nucleolus. Their average dimension is .0057 by .0107 mm. 

 On the basis of development these cells may be divided into 

 three groups. This is a purely arbitrary division and is based 

 on the development of cell processes, (i) A very few gang- 

 lion cells are found which possess axonic and dendritic pro- 

 cesses (Fig. 38). In such cases the dendrites are short and 



