414: 
We have to deal here only with the nerves. The nerve- 
trunks form, as is well known, in the corneal substance by 
division and anastomosis a rich plexus. What we have said 
with regard to the plexus of the rabbit’s cornea holds true 
equally of this in the frog. Here also we find the nucleus- 
bearing sheath of the same to be a prolongation of the neuri- 
lemma of the trunk,and so also the fibrillz possessing granular 
enlargements and embedded in the sheath, exhibit the same 
relations to one another as those of the rabbit’s cornea. We 
find them here also running side by side, stretched or undu- 
lated, or spirally entwined, or, finally, in many places by 
dichotomous division, forming a network within the sheath. 
We may distinguish these branches of the plexus as nerves 
or bundles of the first order. From them branch forth smaller 
bundles, which for a short distance have a serpentine or 
rectilinear course. They possess no sheath of Schwann, and 
hang together by a few anastomoses to form a not very 
dense plexus. ‘These we will call nerves or bundles of the 
second order. They give off after a longer or shorter course 
numerous lateral fine fibres, or terminate in several such 
fine fibres arising at one point. These we will call nerve- 
fibres of the third order. ‘Vhey are distinguished by the fol- 
lowing characters:—(a) Apart from their size, varying only 
within small limits, they possess more or less regularly placed 
varicosities stained dark by the gold. The clearer portions 
removed in the form of a cauterized membrane, and then after an interval of 
a quarter to half an hour, a few drops of a twenty per cent. soluticn of gold 
chloride are allowed to fall on the ash-coloured cornea, and then, after fif- 
teen to twenty minutes the cornea is sliced off with a razor, and for four 
and twenty hours is placed in the light in very slightly acidified water, and 
is examined by means of horizontal sections, or by thin layers torn off, we 
find remarkable appearances. More or less darkly grey-coloured are are 
separated from circumscribed violet-red-coloured ares by darkly red- 
coloured intermediate aree. In the first of these the branched spaces are 
seen embedded in a yellow-brown ground substance, in the second the same 
spaces are embedded in a violet-red ground substance, and in the third 
we find only sharply-outlined, uniformly-granulated, branched, dark-violet- 
red corneal corpuscles. The nearer one approaches the central region, the 
more clearly do the characteristic nuclei of the corneal corpuscles make their 
appearance in the spaces; and, secondly, a substance at first of a pale blue, 
then violet, then dark violet, is more and more to be seen filling up the 
spaces. It is possible, without much trouble, to find places where branched 
clear spaces and branched dark and violet coloured cells, sharply defined in 
all their parts, are so situated that the processes of the coloured cells on the 
one side project into the channels of the clear spaces, and on the other side 
are in connection with the processes of other red stained cells. I cannot 
conceive of appearances more significant than those which the method just 
described afford. Should, however, any one still maintain in the face of 
these facts, that after all these very figures stained by the gold are not in 
reality pre-existing formations, then I cannot help him further. 
