TERMINATION OF NERVES OF MAMMALIAN CORNEA. 465 
disturbing the subepitheiial network, which is left untouched. 
Cohnheim (1. c., p. 41) mentions this already of the cornea 
which has been macerated in acetic acid after chloride of 
gold, and I can fully confirm him herein. This could not 
possibly be the case if the subepitheiial network were not 
situated underneath the deepest layer of the epithelial cells. 
From vertical sections of the rabbit’s cornea we obtain the 
conviction that the greatest number of these fibrils are 
situated above (^.e. anterior, to) Bowman’s membrane. 
Cohnheim does not admit for the rabbit’s cornea a structure 
comparable to the similar membrane in the human cornea 
there can be no doubt about its presence, and in gold 
specimens it is occasionally well marked as a conspicuous 
layer of the thickness of a lamella of the ground substance, 
from which it differs by its being differently coloured, but it 
is of the same tint as the membrana Descemeti. 
Having passed into the epithelium, the nerve-fibrils ascend 
in a vertical manner, winding their way between the columnar 
cells of the deepest layer,, as was first seen by Hoyer, and 
afterwards, by means of his chloride of gold method, minutely 
traced by Cohnheim. As regards the fate of these intra- 
epithelial fibrils there is even less agreement than of that of 
the subepitheiial ones. With the exception of Inzani, Than- 
hoffer, and Ditlevsen, all observers agree that the intra- 
epithelial fibrils extend to near the surface of the epithelium. 
According to Cohnheim (‘Virchow’s Archiv,’ Band 88), 
having arrived in the superficial layers, some of them branch, 
others not, and then they change their vertical course into a 
horizontal one. Some of them terminate with a minute end 
knob freely floating in the precorneal fluid. Kdlliker 
followed the last termination of the intraepithelial fibrils as 
horizontal fibrils situated between the most superficial layer 
of the flattened epithelial cell. Here they run for a longer 
or shorter distance, branch repeatedly, and anastomose but 
rarely, and finally each fibril terminates with an end-knob 
underneath the most superficial layer of the epithelial scales, 
Engelmann (‘Die Hornhaut,’ Leipzig, 1867), whose obser 
vations refer only to the cornea of the frog, saw only free 
ends of the intraepithelial fibrils between the epithelial cells 
of the most superficial layers. At a similar conclusion 
arrived also Tolotschinow (Inaugural dissertation (St. Peters- 
burgh, 1867). According to Petermoller the intraepithelial 
fibres form networks in all layers of the epithelium. In my 
paper on this subject in this Journal I have described them 
as giving of lateral branchlets, and as forming a deep and 
