304 S. WATASE. 



Tlie iiKiin body of tlic ijaiii^lion cell wliero tlic micleiis is 

 Bituated is found in the lower part of tlic oniniatidiuni, occupy- 

 ing in most cases a!i eccentric position. Figs. 13, 14: and 15, 

 PI. XXX, show three ganglion cells completely isolated from 

 the rest of the retinal cells. In Fig. 10, PI. XXX, tiio relation 

 of the ganglion cell to the retinula cell is well shown. 



The ganglion cell is distinguished by constant and well marked 

 features from the rest of the oniniatidial cells. The cell is 

 bi-polar, the one process going upward and outward through the 

 axial channel of the ommatidium (the axial canal of the rhab- 

 dom), and the other going downward and inward to the sub- 

 ommatidial plexus and thence to the brain. For the sake of 

 convenience the former will be designated as the axial process 

 {Ax.p, Figs. 13, 14, etc.), and the latter as the optic nerve process 

 {Oj). n, Figs. 13, 14, etc.) of the ganglion cell. 



The axial process gradually tapers to a narrow point. The 

 process consists of a bundle of extremely fine fibrils, which are 

 distinctly seen as a series of longitudinal striae. For some 

 mechanical causes, the distal process was seen split into three 

 main branches in one specimen (Fig. 15, PI. XXX); in another 

 gpecimen (Fig. 10), the topmost end of the axial process was seen 

 completely macerated into a number of component fibrils, the 

 whole showing a brush-like appearance. 



The large, translucent, spherical nucleus (i\^. Figs. 10, 13, 14, 

 15, PI. XXX), with its nucleolus, is found in the substance of 

 the cell body proper. The position of the nucleus is very often 

 eccentric, as in Fig. 14. The nucleolus is surrounded by con- 

 centric markings in all cases. Between the nucleus and the 

 proximal process there is always a larger or smaller patch of 

 pignient granules {Pff.p, Figs. 10, 13, etc.). The color of the 

 granules ranges from light yellow to dark brown or even to jet 

 black. The yellow-colored pigment is diti'used more or less 

 widely through the body proper of the ganglion cell. Even 

 in the same patch of pigment in tlie cell there are different 

 gradations in the color. From the nature of the drawing used 

 in the present paper 1 cannot show these gradations. Pigment 

 patches iiiay exist in other parts of the cell, but they never form 

 60 constant a characteristic as the group between the proximal 

 process and the nucleus. 



