1897.] The Optic Lobes of the Bee’s Brain. 371 
preparations by von Rath’s platino-aceto-picro-osmic acid, or 
by my formalin-copper-l toxylin, method, and in one in- 
stance I was able to follow through consecutive sections, in a bi- 
chromate of silver preparation, the entire course of the fibers 
from the cells in their antero-superior position in the central 
cerebrum to their T-like branching before the outer stalk, and 
thence into the inter-lenticular portion of the second fibrillar 
body. 
The other group of fibers, after passing inward and slightly 
downward for a short distance, turns and passes backward 
between the inner fibrillar body and the central cerebrum, 
entering the latter posteriorly at a level below the roots of the 
mushroom bodies. This I have described as the antero-posterior 
optic tract (a. p. o. t.). $ ; 
Just where the cells of origin of this tract of fibers are 
situated has not yet been determined. It may, however, be 
mentioned, that I have found in preparations by the bichro- 
mate of silver method, cells, situated near the anterior edge of 
the second fibrillar mass sending, in several cases, their pro- 
cesses into the loose inter-lenticular mass. It may be that 
these are the cells of origin of the tract (4). 
Tracts of fibers are likewise found issuing from the inter- 
lenticular space of the inner or third fibrillar body. They are 
not, however, restricted to one spot in finding egress, but issue 
along the entire hinder margin of the body; and it is rather 
difficult to distinguish them otherwise than as the posterior 
optic tracts. Their number varies according to the plane of 
sectioning, and, it may be, also with different individuals. 
There are chiefly to be noted, however, first, an upper tract 
that seems to pass over the median line of the brain to the 
inner body of the opposite lobe. This tract undoubtedly gives 
off branches by the way, and it is possible that the cells of 
origin of its fibers are to be found on the posterior side of the 
brain below the inner mushroom bodies. At a level somewhat 
below the inner roots of the mushroom bodies there is another 
tract that takes a nearly straight course from one inner body 
to the other on the opposite side of the brain. From this tract 
Viallanes was unable to find evidence of lateral fibrillar 
