Berger, Eyes of Cuhomedttsee. 



227 



in part projected into the vitreous body while that of the other 

 kind, the short pigment cells^ is not projected ; 2nd, both kinds 

 are distally continued into rods which are readily to be distin- 

 guished by their difference in size and by the fact that the rods 

 of the long pigment cells pass between the prisms while those 

 of the short pigment cells pass through the prisms of the vitre- 

 ous body ; 3d, by a probable difference in their nuclei ; 4th, by 

 their central continuations, — the central end of the long pig- 

 ment cells being continued into several processes, while that of 

 the short pigment cells is continued into a single process. Fig. 

 5, also 4, 3 and 2. 



Conant maintained that two kinds of cells could not be 

 distinguished by their pigmentation, and although he had evi- 

 dence of the existence of r 

 two kinds of rods in the 

 vitreous body he was not 

 certain but that the short 

 pigment cells might be 

 changed to the long pig- 

 ment cells by simply pro- 

 jecting their pigment. 

 This I do not think can be 

 the case for in the first 

 place the two kinds of rods 

 are too unlike and without 

 doubt the one kind passes 

 between the prisms while 

 the other kind through the 

 prisms. Conant simply 

 left the question open, 

 hoping to clear up the 

 point on the new material 

 which he preserved. 



To Conant wholly belongs the credit of having first dem- 

 onstrated the prismatic structure of the vitreous body. This 

 can readily be seen in transverse sections of the vitreous body 



Explanation to Fig. 4. This shows a 

 transverse section of the vitreous body 

 quite near to the retinal cells. The section 

 is not exactly transverse, but nearer to the 

 retina on the left side than on the right, in 

 consequence of which the pigmented por- 

 tions {LP) of the long pigment cells are 

 cut on the left while more to the right their 

 rods {R) only are taken. These long pig- 

 ment cells and their rods are readily seen 

 to he in the spaces between the prisms rep- 

 resented by the polygonal areas. SP refers 

 to a prism with its central rod repreented 

 by a dot. 



