Ken YON, The Brain of the Bee. l8l 



The Antero-posterior Optic Tract. 

 This has been well described by Viallanes (^7 ) in his me- 

 moirs on the hexapod brain and also by Cuccati (gs) in his 

 paper on Somoviya eiythrocephala. Like the tract last described 

 it is formed from the fibers coming from the central portion of 

 the outer optic fibrillar mass, which it leaves at the same point. 

 Leaving the antero-superior tract at the optic mass it takes a 

 backward and somewhat inward and downward course through 

 the intervening mass of cells, passing over the anterior optic 

 tract and between the inner optic mass and the central portion 

 of the proto-cerebron and turns into the latter at its postero- 

 lateral lower angle. After entering here the fibers separate 

 from one another and branch, but may be followed for some 

 distance towards the median line. Where its cells of origin are 

 to be found I cannot say definitely. But in certain of my bi- 

 chromate of silver preparations I have seen processes from cells 

 in a group near the starting point of the tract entering the 

 fibrillar mass, and it is not improbable that they are the cells of 

 origin of the fibers of this tract. 



The Posterior Optic Tracts.^ 

 Of the remaining tracts connecting the optic lobe with the 

 central proto-cerebral mass, there are several ; but before pro- 



*The following shows to what extent my results correspond with those of 

 Viallanes (87) who found four and I five tracts connecting the optic lobe with 

 the central cerebral mass : 



A. Connections with the outer optic mass. 



1. Faisceau sup^ro-antereur = 

 Antero-superior tract mihi. 



2. Faisceau sup^ro-postereur = 

 Antero-posterior optic tract mihi . * 



B. Connections with the inner optic mass. 



3. Faisceau inf6ro-antereur = 

 Anterior optic tract mihi. 



4. Faisceau inf^ro-postereur, 2 tracts = 

 2 of my posterior tracts. 



In his work on the grasshopper (88) he was unable to find the two tracts 

 from the outer mass, while from the inner mass he found arising two tracts > 

 one corresponding to my anterior optic tract, the other — his cordon commis- 

 sural — to my lower optic commissure. 



