4.09 
is perfectly fit for preparation. If the cornea is cut out 
fresh, coloured in good gold solution, and carefully treated 
afterwards, success is certain. The flake-preparation which 
I employ for the study of the fine nerves lying surperficially, 
I make by pulling off the epithelium along with quite a thin 
layer of the corneal substance by means of a pointed forceps 
beginning at the scleral border—a proceeding which after 
some practice is accomplished without difficulty. Vertical 
as well as longitudinal sections are employed with good 
results. On such a flake preparation just mounted there 
appear not only the plexus of the more deeply lying nerves, 
but also those lyingin the most superficial layers of the propria 
of the cornea. Besides these we see many of the fibres 
which form the subepithelial network, and several of those 
which run in the epithelium. What, however, comes into 
view with greater clearness is, that the epithelium is quite 
homogeneous over large tracts, and with moderate powers 
we can distinguish none of its elements. We recognise only 
the upper and under surfaces, respectively the anterior and 
posterior bordering surfaces of the same. ‘The former is 
recognisable by means of the precipitate lying irregularly 
dispersed upon it, the latter by an extraordinarily pale 
mosaic, in some places more, in other places less indistinct. 
With stronger powers (450 diam.) we may even recognise just 
a slight indication of nuclei in the flat cells lying superficially. 
Further on we shall see of how great advantage this condition 
of the epithelium is in tracing the nerves withinit. Itis a 
matter of no consequence whether we preserve such prepa- 
rations in the light or in the dark. After one or two days 
they become decidedly darker and the nerve-fibres are per- 
fectly visible to their finest ramifications. Since the prepara- 
tions thus become darker, it is very important that their 
thickness should not exceed a certain degree. If we have 
taken care that they contain only the epithelium and the most 
superficially lying layers of the corneal tissue, so, indeed, 
that the preparations may be penetrated through its whole 
depth by No. 8 Hartnack, we may be sure that they will be 
quite useful for a long time to come. I have in my posses- 
sion some preparations which were made more than six 
months ago; and yet if the examination of these be only 
undertaken with good light, the relations of the finest nerves 
are to be seen with all the perfection to be desired. 
It is by no means part of the plan of this treatise to describe 
minutely the distribution of the more deeply placed plexus 
of broader nerves, nor the subepithelial network of the fine 
nerye-fibres. This is all the more unnecessary, since I could 
