Kenyon, The Brain of the Bee. 153 



columns or stalks present a nearly circular outline and are 

 distinctly delimited from the surrounding mass of fibrillar 

 substance. 



The Roots of the Mushroom Bodies. 



At the place of union of the two stalks there are given off 

 two masses of fibrillar substance of cylindrical shape, but with 

 a diameter considerably greater than that of the stalks. One 

 extends obliquely downwards towards the median plane of the 

 brain where it nearly abuts against the one from the opposite 

 side (fig. 2, PI. XIV). Sometimes, as shown in the figure, 

 the point of one may slightly overlap the other. Like the 

 stalks, this structure is easily distinguishable from the surround- 

 ing mass of fibrillar substance even in ordinary preparations. 



The other, which may be distinguished from the one just 

 described, or inner root, by terming it the anterior root, ex- 

 tends straight forwards and abuts against the peri-cerebral 

 membrane. It is longer than the inner root, but has nearly the 

 same diameter. In section it is nearly circular (fig. i, PI. XIV), 

 and in the transparent preparations in toto appears as a circular 

 body in each proto-cerebral lobe, considerably above the an- 

 tennal lobe. For most of its course it is well delimited from 

 the surrounding mass, but anteriorly it becomes fused with the 

 surrounding fibrillar substance on its lower inner side. In this 

 region it may be seen to be entered by many irregularly branch- 

 ing fibers, even in preparations stained with haimatoxylin (fig. 

 I, PL XIV). 



THE MINUTE STRUCTURE OF THE MUSHROOM BODIES. 



In sections cut in the frontal plane and treated with sul- 

 phate of copper and haematoxylin the cells filling the cups of 

 the mushroom bodies appear to be of two kinds, both arranged 

 one above the other so as to present the appearance of tiers ar- 

 ranged more or less radially with respect to the calyx as a cir- 

 cumference. Laterally they are much larger than those in the 

 middle, which in such sections form a dark colored triangle 

 (fig. I). Those at the side are much lighter. In sections 

 of brains fixed and colored in von Rath's platino-osmo-picric acid 



