BRAIN OF THE 'WHITE ANT' 567 



peculiar characteristic pattern by which these cells may be 

 recognized. 



Although the nerve cells are of similar size throughout the 

 mushroom bodies, they are differentiated into groups, or zones, 

 according to their position. In the center of each cup or calyx, 

 as seen in section (fig. 4), lies an oval mass of cells, /, which is 

 homologous in position with the central oval mass of large cells 

 found in the bees, Jonescu ('09), and in the ants, Pietschker ('11), 

 Thompson ('12), and which I have termed Group I. On each 

 side of Group I, are broad wedge-shaped masses of cells (fig. 4, 



III II 



I 



II, 

 III . 



Fig. 4 Diairram of a mushroom body, showing the nerve cell layer flivided 

 into groups, the calyces, and tho bos^inning of the stalk. /, cell group I; //, cell 

 group II; ///, cell group III; gl., glia cells. 



//), which occupy most of the dorsal surface of each lobe and 

 whose inner margins overlap and enclose the central group I. 

 These masses, which appear separate in sections, form a con- 

 tinuous zone if seen in surface view, and are homologous with 

 Group II of ants. Again, in each lobe, on each side of Group II 

 lie smaller masses of cells which form the lateral surfaces of the 

 lobes (fig. 4, ///). There are only three, instead of four, of these 

 cell masses, because the inner lateral surfaces of the two lobes 

 are in contact and their cells are continuous. These groups are 

 equivalent in position to Groups III and IV of the ants. 



b. The fibrous core of the mushroom bodies. The cups or calyces 

 of the inner and outer lobes of the mushroom bodies are com- 

 posed (1) of converging bundles of fibers, the axons of the three 



