Kenyon, TJic Brain of the Bee. 185 



optic and antennal lobes also enter this region, very much care 

 is necessary in distinguishing the different tracts, but since they 

 fuse to some extent upon entering the calices, it is impossible to 

 follow any one of them singly. Viallanes probably correctly 

 interpreted this bundle as a commissure between the two pairs 

 of mushroom bodies. There is apparently very little probabil- 

 ity of any of its fibers reaching the optic lobes, though none of 

 the methods employed by me have thus far demonstrated con- 

 clusively, that they do not, nor have I been able to determine 

 their exact terminations in the calices nor the location of their 

 cells of origin. In preparations with hiematoxylin and with 

 osmic acid processes from the cells behind the inner side of the 

 inner stalks have been traced upwards and forwards, apparently 

 passing into the commissure as it passes around the stalks, but 

 no such fibers have been found impregnated in brains prepared 

 according to the bichromate of silver method. This negative 

 evidence is not, however, at all conclusive since a sufficiently 

 large number of brains have not been treated. 



The Anterior Coniuiissnre. 



The small band of fibers composing this commissure was 

 first discovered by Viallanes (s?) as connecting the two optic 

 bodies. It may be followed in ordinary preparations without 

 much difficulty from the posterior margin of one optic body 

 across the anterior region of the brain and below the roots of the 

 mushroom bodies to the optic body of the opposite side. Ap- 

 parently its fibers originate from the group of cells immediately 

 inside of and below the body. The processes from the cells 

 seem to pass upward, and after sending a short process into the 

 body where as seen in bichromate of silver preparations, it 

 branches very profusely, and then passes across the median line. 

 I have not been able to determine exactly its termination on the 

 opposite side or whether it or any of its branches penetrate the 

 optic body here. One bichromate of silver preparation where 

 the fibers of the tract are most completely impregnated is incon- 

 clusive from the very fact of the extent of the impregnation. 

 From it one might conclude that branches pass into the optic 



