Kenyon, The Brain of the Bee. 191 



takes them down in front of the fibrillar arch to terminate final- 

 ly, as apparently shown in copper-haematoxylin preparations 

 cut sagittally, in the tubercles of the central body. 



The others form a broad band of fibers passing down be- 

 hind the fibrillar arch to which, as suggested by Cuccati (ss). 

 some of them may give off branches. Certainly some of the 

 smaller fibers cannot be traced below this level (PI. XVI). 



Both the anterior and the posterior groups are composed of 

 two kinds of fibers, one enormously large and the other of or- 

 dinary size. The large fibers are very noticeable in prepara- 

 tions by the copper-ha;matoxylin method from the fact that 

 they stain but slightly and thus appear as light colored spots in 

 a deeply colored surrounding mass of cells (fig. 7-9). Similar 

 results are obtained with von Rath's platino-osmo-aceto-picric acid 

 mixture. The unstained fibers look very much like sections of 

 tubes. But in preparations treated with Weigert's haematoxylin, 

 or in those after-stained with fuchsin the fibers stain more or less 

 deeply and thus demonstrate that they are at least not empty 

 tubes. Even in preparations by my copper-hsematoxylin method 

 staining sometimes takes place. In such cases the inner mass 

 appears in section to be shrunken away from the surrounding 

 fibrillar wall, but remaining connected with it by slender fila- 

 ments. This would seem to show that they are not formed 

 upon exactly the same plan as other nerve fibers. A careful 

 histological study of their structure is necessary. 



The nerves thus constituted may be followed for some dis- 

 tance below the fibrillar arch, but seem to branch and gradually 

 decrease in size. This is noticeable in the figures, where in 

 fig. 7, the anterior nerve appears with three large fibers and at 

 a considerably lower level (fig. 9) there is but one. The fibers 

 of this nerve soon become untraceable and appear to pass into 

 the fibrillar arch and the ocellar glomerule beneath. 



Some of the fibers of the other two nerves seem to termi- 

 nate in the same way, but a large number of the larger fibers 

 continue downward, as seen in both horizontal and frontal sec- 

 tions, until they reach the neighborhood above the oesophageal 

 foramen, where they separate. Some seem to terminate in this 



