Nucleoli (luring- the Oogenesis of the Diaguu-tlv. 215 



(iva. Perez (1886) and Gross (1900 and 190;V) also found the fila- 

 ment distinctly separate from the germ-cells and serving only as a 

 suspensory ligament. In Collembola. according to Lecaillon ( 1901), 

 the germinal area is situated in the middle of the ovary, yet the 

 end-filament is attached in front, far away from the germinal area. 

 Marie Daiber ( 1904) in Bacillus rossii says that the end-filament is 

 merel}' suspensorial. In the dragon-fly. however, there seems to be 

 a direct continuity between the cells of the filament on the one hand 

 and the germ-cells and follicle-cells on the other. 



2. The Germinal Area. 



It is in the germinal area that the ditterentiation of the filament- 

 cells into germ-cells (e in Fig. 1 and 39) and follicle-cells (/' in 

 Fig. 1 and 39 ) takes place. The germinal area is distinctly marked 

 oif from the end-filament and the growth-area, and showing, in cross- 

 section, a mass of cells, instead of a single cell, as in the case 

 of the filament, and a single cell surrounded by a layer of follicle- 

 cells in the growth-area. Fig. 2 and 9 show cross-sections of the 

 germinal area of Flcdhemis and Fig. 41 and 44 of Anax. Fig. 1 

 is a longitudinal section of the same area in Platheniis, Fig. 39 in 

 Anax. Adjoining the filament, cell boundaries are absent and the 

 cells unite to form a syncytium. 



a) The Follicle-cells. 



The follicle-cells can easily be traced back to their origin from 

 cells of the end-filament which in this case are the primitive ova, 

 and down even to the end of the growth- area of the egg-string- 

 their structure is almost identical with that of the filament- cells. 

 They have the same clear cytoplasm, indistinct cell-boundaries and 

 single oxyphile nucleolus. They lie wedged in between the rapidly 

 differentiating germ-cells, becoming flatter and flatter as the latter 

 increase in size. In no case is there any indication that follicle- 

 cells arise from elements which have developed for a time as oogouia, 

 and then, because of crowding, have degenerated into follicle-cells. 

 The material, however, does show a variable number of cells which 

 give evidence of degeneration ((j in Fig. 1 and 39) their chromatin 

 being densely massed and the cytoplasm clear. I think these are 

 degenerating follicle-cells rather than oogonia. It is probable that they 

 represent food-cells. They only occur in the germinal area, and are 



