376 SPECIAL HISTOLOGY. 



are associated into larger and smaller compressed bundles, 

 usually 0*01 — 0*01 2'" wide, which either mutually anastomose 

 at very acute angles or run for considerable distances parallel 

 with each other. Notwithstanding all that has been stated by 

 various authors, it may be boldly asserted that the terminations 

 of these nerves are as yet wholly unknown ; and, as more will 

 be said upon this subject afterwards, I shall here merely 

 remark that, in any case, they exist not only in front, but in 

 every part of the retina, because the layer of nerve-fibres 

 becomes visibly thicker from before to behind. I have esti- 

 mated its thickness, in Man, at the bottom of the eye at 

 0-036"', two lines beyond the yellow spot at 0*006— 0'008 ,,/ , 

 and near the or a serrata at 0002'". 



5. The limitary membrane, membrana limit ans 1 (b), is a 

 delicate membrane, 00005'" thick, intimately united with the 

 rest of the retina, which, when that structure is teazed out, 

 and on the application of reagents, is frequently detached in 

 large shreds, and then appears perfectly structureless. On its 

 inner aspect, towards the hyaloid membrane (a), when the 

 retina is folded, flattened cell-nuclei are occasionally per- 

 ceptible, which certainly cannot be referred to an epithelium, 

 and scarcely to the vitreous body, as the latter is always 

 readily separable from the retina. It seems to be different 

 with regard to a clear, light yellowish border, 0*002 — 0003"' 

 wide, situated on the outer side of the membrana limitans, 

 which, in folds of a perfectly fresh retina, appears, as it were, 

 to be completely blended with the limitary membrane, but 

 occasionally exhibits, more or less distinctly, the contours of 

 excessively clear and transparent spherical bodies (b), 0*002 — 

 0003'" in size. At a longer interval after death, as well as on 

 the addition of water, a large number of transparent globules, 

 like drops of albumen, are afforded by the clear border of the 

 retina, which then disappears altogether, except the membrana 

 limitans, frequently also, together with it. Todd and Bowman 

 describe the clear bodies above noticed as cells and also figure 

 a minute nuclear corpuscle in them ; and I will not directly 

 contradict this notion, although I have not as yet been in any 

 way able to satisfy myself of the existence of nuclei and true 

 cells in this layer. 



1 [So named by Pacini (1. c, p. 22). — Eds.] 



