TERMINATION OF NERVES OF MAMMALIAN CORNEA. 463 
was already known to Cohnlieiin, Kollikev, and Hoyer ; as 
Cohnheim very beautifully showed, they come olf from the 
rami perforantes in bundles,” except in a small central 
zone. But 1 would add here that there exist ‘ bundles ’ also 
in the central zone, but they are not so conspicuous, because 
smaller. All fibrils are possessed of varicosities, and those 
of the same bundle diverge the further away from their 
ramus perforans ; they form triangular groups, the apex of 
which is directed towards the periphery. 
(d) A few fibrils are derived from the intrabasilar fibres, 
as mentioned above. 
As regards the course of the fibrils of the subepithelial 
network, they all have a linear, but more or less winding 
course. Their number is everywhere very great, but there 
exist remarkable differences in this respect in different 
specimens. Both rabbits’ and guinea-pigs’ corneae, prepared 
with the chloride of gold, with or without subsequent re- 
duction by formic acid, tartaric acid, warmth, &c., show 
some striking variations. The best results, e. the greatest 
number of these subepithelial fibrils, I have noticed in 
cornea) prepared, after chloride of gold, with tartaric acid 
(see my paper in this Journal, October, 1871, p. 408), or 
with glycerine (in the ^ Monthly Micr. Journal,^ April, 
1872, p. 157). 
In successful specimens so obtained the number of 
fibrils is here astounding ; it is so great and dense that we 
can truly speak of a special nervous layer formed here by 
fine fibrils. Such specimens are not common ; they are, in 
fact, rare ; perhaps only one out of ten will show them to 
perfection ; but, since we cannot assume that this one would 
in reality differ from the others, we must necesssarily con- 
clude that this is due to a lucky unknown condition in the 
method of preparation, and I would again insist on this, as 
1 have done in my former papers, viz. that the description 
of the distribution of the fine nerve-fibrils is probably the 
correct one, which refers to the most perfect preparations. 
In the s])8cimens that we are now having before us, and 
of which figs. 7 and 8 give a faithful representation of the 
nerve-fibrils of the subepithelial network, it will be seen 
that the individual fibrils are of very great length, but there 
are differences in this respect. In fig 8 I have drawn, very 
accurately, a great number of the fibrils (by no means all) of 
the subepithelial network of a portion of the cornea, amount- 
ing ill length to about 0*4 mm., and it will be found that 
some fibrils exceed this length, while others fall far short 
of it. 
