Ken YON, TJie Brain of the Bee. 199 



a tract passing into the fibrillar substance towards the median 

 line of the brain. 



III. Below the anterior optic tract nearly halfway between 

 the inner optic mass and the optic body is a group of mod- 

 erately large cells, the tract of fibers from which passes under 

 the optic tract and upwards towards the middle superior surface 

 of the anterior root of the mushroom body, above which they 

 seem to branch. In all preparations where seen there is consid- 

 erable difficulty in distinguishing the fibers of this tract from the 

 outer branches of the tract from the posterior region of the 

 calices to the root. 



IV. Immediately outside of and below the optic body is 

 a similar group whose processes pass beneath the optic tract 

 upward and inward, apparently, along the lower surface of the 

 anterior root. 



V. Inside of and below the optic body is a group of cells 

 of median size whose fibers pass upward along the outer side of 

 the anterior root. 



VI. Below these and above the antennal morula is a 

 group that sends a tract of fibers upwards across the inner side 

 of the root (figs. 24 and 31, fiber 10 of the diagrams). 



VII. Outside of these and above the morula are three 

 small groups that send as many tracts of fibers inward to the 

 central body (fiber 30). They pass below the latter structure 

 and, turning upwards in front of the tubercles of the central 

 body, enter the space separating its dorsal and ventral portions. 

 Apparently they form the tract that is figured by Bellonci (82) 

 as connecting the inner antenno-cerebral tract with the superior 

 commissure on the opposite side of the brain, or as forming a 

 chiasma with its companion from the opposite side. 



VIII. Near the latter group is another whose processes 

 form the outer antenno-cerebral tract (fig. 24). 



IX. Beneath the calices and in the median plane is a 

 group of cells recognizable in fig. i, the processes of which pass 

 directly downward, and according to Viallanes (ss) enter the 

 oesophageal commissure of the brain, thus forming a chiasma. 

 In the wasp (Viallanes 87) and in Soinoniya (Cuccati 88) their 



