44 JouRNAL oF COMPARATIVE NEUROLOGY. 
The optic tracts, that portion of the nervous tissue 
which lies between the optic lobes and the optic chiasma, are 
entirely wanting. The space occupied by these tracts in the 
normal brain (Fig. 8, 7) is, in this brain, partially occupied by 
tissue in which I have not been able to make out any structure. 
All the stains that have been tried have failed to reveal any 
cells. These tracts do not take the stains with the same readi- 
ness and in the same degree that normal brains do when sub- 
jected to exactly the same treatment. Three fish, the Ambly- 
opsis, Campostoma and Eupomotis, were killed and the heads 
placed in Fout’s mixture for the same time. The brains were 
then removed from the skull as soon as they were sufficiently 
hardened. They were then placed in the same bottle in order 
that the conditions might be the same. The three were im- 
bedded in the same block, and sectioned side by side. The 
tissue of the tracts of the brains of Campostoma and Eupo- 
motis differentiated very well—but the degenerate brain showed 
no structure. 
In the dissections of the head of the blind fish, I have 
been unable to find any indications of optic nerves leaving the 
lobes. In both the dissections and the sections which have 
been made of the entire head and brain, there seems to be no 
break in the enveloping membranes on the anterior ventral sur- 
face of the lobes where the optic nerves originate. The 
vestiges of the optic nerve can be followed backward from 
the eye for a short distance. The only tracts leading away 
from the lobes are those which connect them with cerebral 
hemispheres and cerebellum. Those which pass forward to the 
hemispheres are from the diagonal fibers of the fifth layer. 
These pass laterally, but before reaching the lateral aspect of 
the lobes turn downward through the granular layer and epi- 
thelial layer, and then course forward toward the ventral surface 
of the hemispheres. 
