57G 



TEXT-BOOK OF ENTOMOLOGY 



rudiment consists, then, of a string of cells lying on each side in 

 the dorsal wall of the primitive segments, which extend from the 

 2d to the 7th abdominal segments. In the formation of these strings 



or rows of cells not only are the genital 

 cells concerned, but also still undiffer- 

 entiated mesoderm cells (Fig. 540, B, C), 

 which originate from the dorsal wall of 

 the coelom-sacs arid lie next to the genital 

 cells. Some of these last tend to envelop 

 the genital cells. We designate them the 

 epithelial cells of the genital rudiments 

 (ep), while others form a cellular cord 

 which takes a position medial and ven- 

 tral to the genital cells. 



From the genital cells in the female 

 arise only the egg-cells (and the nutritive 

 cells in those forms which have such). 

 The follicular epithelium of the egg- 

 tube, on the other hand, also the corre- 

 sponding cells of the ter- 

 minal chamber, originate 

 from the epithelial cells. 

 Phyllodromia and Orth- 

 optera in general, to 

 which this description 

 applies, show in this 

 respect tolerably simple 

 relations, since the ger- 

 minal or terminal com- 

 partment of the ovary in 

 them is composed of rela- 

 ; . , .'' ' tively few cells. In most 



other insects, and espe- 



FIG. 549. Sagittal (longitudinal) section through the '-IT .1 !-,'/>!-, !, 



abdominal part of a primitive band of cockroach (Phyllo- CiaiJy tllOSe WniCn Have 

 dromia germanica) after the end of the formation of the 

 primitive segments: 1-7, 1st to 7th abdominal segments; 

 from the Sth abdominal segment (8) to the last segment (es) 

 extends the inturned ventral part of the primitive band; 



rn-pof rmmViPr nf fnnrl- 

 * glcdi 1 



no 11 ;,, 4-l 10 rivavir -f-Via 



L 



am, amnion ; c, coelom-sac ; d, yolk; gz, genital cells, lying rrorinincil nTiamVipr /TTpim- 

 partly in the dissepiments, partly in the wall or in the cavity germinal C 



of the primitive segments. fach) is extraordinarily 



large. 



The ventral cellular cord (cz) develops into the proximal part of 

 the oviduct, which widens out and receives the single egg-tubes. 



The coelom-sacs in the farther course of their development, 



