BRAINS OF THREE GENERA OF ANTS 529 



larnervenbriicke," although applicable to the honey bee and to 

 some ants, is a misnomer in the case of certain other ants. Fig- 

 ures 14 and 15 show us, first, that in the queen of Lasius niger, ' 

 the fibers of the ocellar nerves pass into the protocerebral lobes 

 together with the last fibers of the first or anterior dorsal com- 

 missure; second, that the ocellar lobes have disappeared from the 

 section in which the posterior dorsal commissure begins. It is 

 plain, therefore, that in the queen of Lasius niger there is no re- 

 lation whatever between the ocellar nerves, and the posterior 

 commissure. The same is true of the Camponotus queen, all 

 the fibers passing into the brain with the last fibers of the anterior 

 commissure, none with the posterior dorsal commissure, which 

 in these two queens is certainly not an '^Ocellarnervenbrijcke." 

 In the Formica queen (fig. 23), the ocellar nerve fibers do not 

 pass to the brain along the anterior dorsal commissure, but go 

 vertically downward through the latter. Von Alten ('10, text 

 fig. 4A), finds a similar arrangement in the brain of Bombus 

 9 . In the workers of Formica and Lasius the ocellar nerve fibers 

 behave like those of the Formica queen, going vertically downward 

 through the posterior dorsal commissure. In the males of all 

 three genera, however (fig. 22), the posterior dorsal commissure 

 does serve as an ''Ocellarnervenbriicke," or path for the ocel- 

 lar nerve fibers, for although some fibers go vertically downward 

 through the posterior commissure, others curve to the right or 

 left and pass along the commissure into the protocerebral lobes. 

 In the case of these three males, therefore, Jonescu's characteriza- 

 tion of the posterior dorsal commissure as a ''chiasmatische 

 Bahn" is most appropriate. Jonescu states further that in the 

 honey bee this commissure originates from cells of the intercere- 

 bral region: ''Sie entsteht aus den Fasern, welche von den Gang- 

 lienzellen der Pars intercerebralis kommen." This is not the case 

 in the ants here investigated, for in all these forms the posterior 

 dorsal commissure can be traced into the fibrous core of the pro- 

 tocerebral lobes. Pietschker (p. 80), states in the text that he 

 agrees with Viallanes, that the commissure originates from the 

 protocerebral lobes, but in his figures 24, 29, 34, he fails to show 

 any origin for it. 



