igo Journal of Comparative Neurology. 



THE DORSO-.VENTRAL TRACT. 



Five tracts of fibers have thus far been described as enter- 

 ing the calices of the mushroom bodies and there still remains 

 another. This was first brought to my notice in a frontal sec- 

 tion of a brain impregnated with bichromate of silver, and was 

 subsequently recognized in a similar section of a pupal brain 

 treated by the copper-haematoxylin method. It begins as a 

 small band of fibers in the region between the two stalks, where 

 branches of it enter both calices, and passes downward be- 

 neath the cells clothing the posterior surface of the brain to the 

 oesophageal foramen, then continues anteriorly along the roof of 

 this so as to reach the opposite side of the brain near the anterior 

 surface. In its passage along the roof of the foramen its fibers 

 send branches into the side from which the main fibers came, and 

 these form an arborescent termination among branches of fibers 

 coming from the ventro-cerebron and the ventral cord. Since 

 these latter fibers cross the median line above the foramen an- 

 teriorly, the passage of the tract to the opposite side brings it 

 into close relation with them along their whole extent along the 

 roof of the foramen. This relation is best shown in plate XX, 

 which shows two fibers of the tract as seen in a single section. 

 The cells of origin of the tract have not been seen. But suffi- 

 cient has been determined to show in what close relationship the 

 cells of the mushroom bodies stand with the ventral nervous 

 system. 



The Ocellar Nerves. 



In the bee the ocelli are situated close together, and as a 

 consequence their so-called ganglia are contiguous and their 

 nerves to a large extent fused. The nerve from the median ocel- 

 lus passes downward and backward between the two inner calices 

 and fusing with the nerves from the lateral ocelli forms with them 

 a single mass that divides to pass around a large trachea piercing 

 the brain in the median line between the calyx cups. Immedi- 

 ately below this the fibers again come into close contact, but at 

 a little lower level some of those coming originally from the 

 median ocellus separate from the rest and follow a course that 



