77 
On the Nerves of the Cornea^ and of their Distribution 
in the Corneal Tissue of Man and Animals. By J. V. 
CiACCio, M.D., of Naples. 
(Read May 13th, 1863.) 
(PI. VI and YII.) 
Since Schlemm^s discovery of the nerves of the cornea up 
to the present time nearly all observers who have investigated 
the subject agree that these nerves^ after dividing and sub- 
dividing, terminate in a wide network, composed of non- 
meduUated or pale nerve-fibres. The ultimate arrangement 
of this network has not yet, however, been fully pointed out, 
neither has any one proved whether it exhibits the same 
arrangement in different animals as in man. With the hope 
of throwing some light upon a subject at present so 
little known, I have made many observations on the cornea 
of the sparrow, eel, frog, mouse, and man, and the conclusions 
which I have arrived at will be detailed in the paper which 
I have the honour to bring before the notice of the members 
of this Society. 
The great importance of the present inquiry, I imagine, 
will be generally admitted. The cornea is endowed only 
with common sensibility, so that when we have established 
with certainty the manner in which the nerves terminate in 
it, we may, with some reason, infer the mode of ending of 
the nerves in the other parts possessing the same kind of 
sensibility. By comparing, then, these results with those 
hitherto obtained by observers, in reference to the ending of 
motor nerves, the debated question about the terminal distri- 
bution of these two kinds of nerves, perhaps, will be finally 
settled. But this inquiry is as difficult as it is important. 
Of the many difficulties which I have met with, I shall only 
now allude to those which seem to me to be the greatest. 
1. The first is, that the nerves of the cornea in all their 
course continually change the plane and direction of their 
distribution, so that in making very thin sections for micro- 
scopical investigation, not only is the relative position of 
nerves and the adjacent tissues altered, but those nerve-fibres 
which we observe in the thin sections very often exhibit such 
appearances that they are hardly recognised by the most ex- 
perienced eye as nerve-fibres. 
2. The second difficulty consists in this, that the optical 
properties of the nerves and other elementary parts of the 
cornea are such that, without the aid of some chemical 
