THE EYE OP PECTEN. 95 



and staining in picro-carmine. There is very little protoplasm 

 round tlie nucleus, and the processes are so irregular that 

 beyond the fact that the cells are multipolar no definite shape 

 can be ascribed to them. They are, on the whole, slightly 

 larger than most of the outer interstitial cells. The processes 

 wrap round the rod-cells, and may even extend through the 

 basal pseudo-membrane between the rods. It has been said 

 by Hesse that the inner interstitial cells are so rare in the 

 centre of the retina that there is only one to four or five rod- 

 cells. They are just as numerous here as elsewhere, except, 

 perhaps, the peripheral modified region. 



Patten and Rawitz considered these cells to be ganglion - 

 cells. Schreiner figured their shape incorrectly (as did I 

 myself in a previous memoir) and found them to be connected 

 with the distal nerve. Hesse also believed these cells to be 

 nervous, for he states that the connection with the distal 

 nerve is sometimes very distinct. In his last paper, however, 

 he has altered his views of the relations between the distal 

 cells and the nerve, and the question of the interstitial cells 

 is therefore left open. Hyde, as already noted, regarded 

 them as bi-polar nerve-cells connected with the axial fibre of 

 the rods. Everything, however, points to the conclusion that 

 the inner interstitial cells, like the outer, are simply support- 

 ing cells, their structure being quite unlike that of nerve- or 

 sense-cells, and no connection with nerves having been found. 



SUB-KETINAL LaYEES. 



Below the retina there is generally a space, a split between 

 it and the next layer, which maybe of considerable size. All 

 writers have figured this, but it is impossible, in most cases, 

 to discover whether they regarded it as normal or not, since 

 only Hesse refers to it, and he regarded it as due to shrinkage. 

 I have figured it as it Usually occurs in sections (PI. 6, fig. I), 

 but it must be remembered that this space is simply due to 

 fixation, etc. In some cases, for example, the next layer, 

 the tapetum (PI. 7, fig. 1, Ta.), will be found for some distance 



