Berger, Eyes of Cubomediisce. 229 



such a cell. Conant also suggests that these prisms with their 

 central fibers are the true visual rods. What then are the long 

 pigment cells with their rods ? 



Since I believe I have evidence to show that the long pig- 

 ment cells can project themselves with a part of their pigment 

 into the spaces between the prisms of the vitreous body during 

 exposure to light while they retract themselves with their pig- 

 ment when in darkness, may these cells not be solely for this 

 purpose — to check the diffusion of light in the vitreous body ? 



The capsule of the lens seems to be homogeneous and ac- 

 cording to Schewiakoff a secretion of the lens cells. The rods 

 from the long pigment cells pass into this capsule (Fig. 5> -^O 

 and the rods of the short pigment cells (better called prism 

 cells) perhaps also do. At all events numerous smaller fibers 

 are seen in the capsule (Fig. 5). 



The lens and cornea I shall not further discuss. Schewia- 

 koff suggests that the eye is of ectodermal origin and that it is 

 an invagination which becomes pinched off as a hollow sphere, 

 the outer portion of which forms the lens the inner the retina 

 and vitreous body. 



The structure of the smaller complex eye is very similar 

 to the larger one except that it has no capsule (Fig. i) to its 

 lens and lacks the long pigment cells in the retina. Dr. Conant 

 gives an excellent figure of this eye in his thesis but does not 

 show the prismatic structure of the vitreous body nor the rods 

 from the prism cells. 



One may regard the three kinds of eyes, the simple, the 

 smaller complex and the larger complex, as so many stages in 

 development. The retinas, the most important parts of eyes, 

 would be homologous and quite at the same stage of develop- 

 ment ; the lenses of the complex eyes would be homologous, 

 but not with those of the simple eyes. The capsule of the 

 larger complex eye stands alone. The vitreous bodies in the 

 complex eyes being homologous cannot be homologised with 

 any thing in the simple eyes unless one regards the so-called 

 lenses of those eyes vitreous bodies and the vitreous bodies of 



