88 
CiAccio^ on the Nerves of the Cornea. 
Having advanced these short considerations on the manner 
in which the nerves of the cornea in their ultimate distribu- 
tion are arranged,, I pass on to say more particularly where I 
have found these distinctions existing. 
1. Network by the coalescence of nerve-branches with one 
another, — I have observed this variety of network in the cornea 
of the sparrow. The trunks of the nerves^ which enter the 
cornea of this little bird^ are seen at different points from 
the corneal margin to divide and subdivide, and the immensely 
numerous branches which result from these repeated divi- 
sions are frequently observed to anastomose with each 
other. When a branch is uniting with another no interlace- 
ment of their fibres appears to take place ; but they seem, so 
to speak, to fuse into a single larger branch. The branches 
generally unite themselves at angles more or less acute ; 
sometimes, however, they appear to unite at regular right 
angles ; and when such occurs, one of the branches forming 
the angle sends out a fibre on each side of the point of junc- 
tion parallel with the other branch. Thus it would appear 
from such circumstances that the arrangement in the cornea 
of the sparrow is the most simple and regular. 
2. Network by the intermixture of the nerve-fibres of one 
branch with those of another. — The second variety of network is 
found in the cornea of the frog and fishes. I have previously 
mentioned that, in the cornea of these animals, the different 
primitive fibres which compose the branches spread out and 
frequently change their relative position. Thence it happens 
that, when one branch unites with another, a very percepti- 
ble interlacement of their fibres takes place. I have often 
followed some trunks to their furthest branches, and ob- 
served that the disposition of these very fine branches is 
the same as with the larger, and that the anastomoses among 
them are of the same character as those between the main 
branches. I think I may safely argue from the above state- 
ments that the networks in the frog and fishes are more com- 
plicated in their formation than that of the sparrow. 
3. Plexus with wide meshes. — The nerves which are dis- 
tributed to the cornea of the mouse terminate in this variety 
of plexus. The ultimate branches of each trunk unite to- 
gether in such a manner as to form meshes which have not 
all the same dimensions, but are in immediate continuation 
one with the other. The meshes generally assume an irre- 
