i8o Journal of Comparative Neurology. 



outer mushroom body, it leaves this other tract and passes be- 

 hind the stalk close to the junction of the latter with the calyx. 

 Whether any of its branches pass into the calyx here I am not 

 able to say definitely, but apparently they do. In preparations 

 with bichromate of silver some at least of its fibers may be fol- 

 lowed across the intervening space to the opposite side of the 

 stalk of the inner mushroom body. Whether any of them con- 

 tinue on into the superior commissural tract my preparations 

 thus far made do not show. 



TJie Antci'o- superior Optic Tract. 



This as described by Viallanes (S7) and Cuccati (ss) starts 

 from the outer fibrillar mass. Instead of originating like the 

 two tracts just described from the radiating fibers of the mass, 

 it arises from the fibers filling the space between its two lentic- 

 ular portions. These fibers are gathered into a bundle and leave 

 the mass at its antero superior edge. Passing backward and 

 inward through the intervening layer of cells, the bundle reaches 

 the outer surface of the central proto-cerebral mass, then turning 

 , upward joins the postero-superior bundle. Just before reaching 

 the stalk of the outer mushroom body it leaves its companion 

 and passes in front of the stalk, close to its junction with the 

 calyx, to the space between the two stalks where its fibers branch, 

 one group passing into the outer, the other into the inner 

 calyx. In one preparation I was able to determine the cells of 

 origin of this tract and to follow it through several sections to 

 its connection with the optic mass. According to the facts 

 shown in this brain impregnated with bichromate of silver the 

 description should be reversed and the union of the tract with 

 the optic mass be spoken of as its terminus, for the cells from 

 which it originates co!n[)rise a small group on the supero ante- 

 rior-lateral surface of the central proto-cerebral mass and send 

 their processes as a bundle of fibers almost directly backward 

 to the space between the two stalks, whence a branch passes 

 into the calices and another to the fibrillar optic mass, as 

 described. 



