BRAINS OF THREE GENERA OF ANTS 535 



into two bundles (fig. 17, st.) so that four of these bundles, or 

 roots, two dorsal and two ventral, are seen in sections of this 

 region, figure 18, d.b., v.h, (p.r.). The fibers of the two dorsal 

 bundles pass immediately upward into the central body and may 

 be termed the central body roots of the mushroom bodies; the 

 fibers of the two ventral bundles, which are identical with the 

 so-called ''tubercles of the central body," but which are actually 

 the posterior roots of the mushroom bodies, continue backward and 

 finally enter the hindermost part of the protocerebral lobes on 

 each side of the median line of the dorsal surface (figs. 18 to 23, 

 p.r.). 



The identity of the posterior mushroom body roots with the 

 ''tubercles of the central body" is so clearly seen in the series of 

 sections shown in figures 17 to 21 that it seems surprising that 

 it has not been observed before. Jonescu has described the cross- 

 ing of fibers from the central body to the "ocellar glomeruli" 

 and indeed in his figure 22 he figures a second round body, un- 

 labeled, on the left side of and above the 'tubercles.' This may 

 indicate that, in the honey bee, the ventral rather than the dorsal 

 bundles, or roots, are connected with the central body, but it 

 is, in my opinion, strong evidence that the "ocellar glomeruli" 

 are identical with the posterior roots of the mushroom bodies 

 in the honey bee as well as in ants. 



9. THE MUSHROOM OR PEDUNCULATE BODIES 



The mushroom bodies have always been objects of great in- 

 terest, both on account of their structural prominence and of 

 the various functions assigned to them by different writers. 

 They have been termed by Dujardin ('50) "les corps pedon- 

 cules;" by Leydig, "die gestielten Korper;" "mushroom bodies," 

 by Kenyon; "pedunculate bodies," by Wheeler; "corpo pedun- 

 colato," Berlese. 



The finer structure of the mushroom bodies may be seen best 

 in frontal sections of the brain. Figures 32 to 40 represent dia- 

 grams of the mushroom bodies, with their fiber tracts and cell 

 groups, as if seen in optical section. The outlines of these figures 



