^^^8 SLONAKER. [Vol. XIII. 



who has found a fovea in the cat. Ganser (19) and Chievitz 

 (31) have found only an area. 



Chievitz has described and pictured the area and fovea cen- 

 tralis in many animals, and put his results in a concise tabu- 

 lated form. Other investigators of this period will be mentioned 

 later in a similar tabulation. 



Many obscure points were made clear by these numerous 

 investigators. However, two points still remained unsolved: 

 the structure of the molecular layers and the endings of the 

 fine branches of the retinal cells. The solution of these points 

 depended on a new method of research. This new method 

 was inaugurated by Tartuferi (21) in 1887, who used the quick 

 method of Golgi and succeeded in showing that the cell pro- 

 cesses end in more or less fine tufts which did not anastomose 

 with other bunches. Later on he discovered and described the 

 structure of the molecular layers. 



Dogiel (22) in 1888 so modified the Ehrlich method that it 

 would stain the fresh retina. He was thus able to confirm 

 almost all the results of Tartuferi. He found that the branches 

 from different cells anastomose, but other investigators have 

 not confirmed this. The works of Baquis (23) and Ramon y 

 Cajal (24), who used the Golgi method, in general confirm the 

 results previously obtained. Ramon y Cajal has made clear 

 the endings of the rod and cone fibres in the outer molecular 

 layer. He finds that there are certain cells of the inner nuclear 

 layer which are related to the cones. That is, their terminal 

 branches come in contact only with the processes from the 

 cones, while other cells of this layer send their dendrites to the 

 rods. In general, each cell communicates with many rods or 

 cones, excepting in the fovea, where the process from each cell 

 branches very little and comes in contact with but one cone. 



Methods. 



As I have only attempted a gross comparison of the areas of 

 acute vision in this study, I have used only those hardening 

 fluids and methods of research which will preserve the eye with 

 the least possible distortion. For fine histological study of the 



