BRAINS OF THREE GENERA OF ANTS 539 



the cup, Group I, are present in the worker as well as in the 

 queen and male. On this point I differ from Pietschker, who 

 does not find these large cells in the worker of C. ligniperdis, but 

 only in the sexual forms. Pietschker ('10, p. 77): "Bei den 

 Geschlechtsformen fand ich die Hohlung der beiden Becher von 

 einer Masse auffallend grosser Zellen angefiillt (Taf. 5, fig. 5, 6 z), 

 wie ich sie bei der Arbeiterin nicht zu bemerken vermochte. Die 

 letztere zeigt kleinere Zellen, welche um so zahlreicher sind." 

 Pietschker also fails to note the arrangement and differentiation 

 of the mushroom body cells into the groups described above. 



Berlese ('09) refers to the small size of the mushroom body 

 cells and to the reduction in their cytoplasm, but does not men- 

 tion the greater size of the cells in the cup. Group I. On page 

 574 Berlese states: 



La cavita del calice e riempita di cellule cromatiche molto piccole 

 (fig. 669 Cr), con protoplasma assai ridotto. La sue parete e formata di 

 sostanza punteggiata, a trama molto serrata. La cellule inviano i lore 

 prolungamenti a questa parete: il fusto trae le fibre che lo compongono, 

 non direttamente dalle cellule ma dalla parete del calice. Questa parete 

 si unisce, all in dentro, alia sostanza del lobo procerebrale a mezzo di 

 un tratto fibroso. II fusto apparisce cosi formato da un fascio di fibre 

 parallele. 



Kenyon states that ''the cells of the hexapods generally 

 are strongly distinguished from nerve cells elsewhere 

 in the brain, and in the whole nervous system for that matter, in 

 being nearly devoid of extra nuclear protoplasm. This fact led 

 Dietl to term them ganglionary nuclei." Kenyon found that 

 ''The cells filling the cup appear to be of two kinds .... 

 Laterally they are much larger than those in the middle." 



Jonescu, in the mushroom bodies of the honey bee, describes 

 three groups of nerve cells filling the cavity of the cup, seen 

 in section as a median and two lateral groups, although in reality 

 the lateral groups form a circle about the median group. The 

 cells of the median group are larger than the lateral ones. Jonescu 

 followed the fibers from these cells into the stalk, and found 

 that the fibers from the large median cells occupied the very 

 center of the stalk with those from the lateral cells outside. 

 The remaining cells of the mushroom body are described as lying 



