Kenyon, TJie Brain of the Bee. 179 



The Anterior Optic Tract. 



Even in ordinary preparations there are indications of fibers 

 passing radially or nearly perpendicularly to its two surfaces, 

 through the inner fibrillar mass. Emerging from the inner sur- 

 face these are gathered into two bundles, the larger of which 

 passes forward, and slightly downward along the outer surface 

 of the central proto-cerebron and finally terminates in a small 

 oval body called by Viallanes ( 87) the optic tubercle, situated 

 immediately above the antennal lobe and to one side and below 

 the terminus of the anterior root of the mushroom bodies of 

 that side. In preparations with bichromate of silver the bundle 

 is often very prominently shown, and in addition also the arbor- 

 escent terminations of its fibers in the optic body, as shown in 

 the diagrams that follow. This body in the bee is divided into 

 a large inner mass and a very small outer mass, and into the 

 latter some of the fibers of the tract send each a small branch 

 before passing on to the larger body. 



Other fibers apparently arising from cells in the immediate 

 neighborhood also branch in the body and connect it with other 

 parts of the brain. One group passes to the opposite side and 

 appears to terminate in the opposite optic body. Others pass 

 backward,, but no tracts appear to connect it with the mush- 

 room bodies, although individual fibers are often found going 

 in that direction. 



The Postero -superior Optic Tract. 



As just indicated, the fibers emerging from the convex sur- 

 face of the inner fibrillar mass divide into a large and a small 

 bundle. The latter may be considered the postero-supenor 

 optic tract, which seems to have escaped the notice of Viallanes 

 (87, 8S)- It may be easily traced in preparations either by the 

 copper-haematoxylin method or by the platino-osmo-aceto- 

 picric acid method of von Rath, and after leaving its larger 

 companion, which is almost immediately, it passes upward along 

 the outer surface of the central proto-cerebral mass, and joining 

 the antero-superior tract, to be described a few lines further on, 

 takes an inward course until, arrived close to the stalk of the 



