374 



CELL-DIVISION AND DEVELOPMENT 



I believe there is reason to accept the conclusion that this relation 

 is one of position, however caused. A central position of the mitotic 



wT B D 



Fig. 175. Embryos of the earthworm Allolobophora fcetida, showing teloblasts or apical cells. 



A. Gastrula from the ventral side. B. The same from the right side; m. the terminal telo- 

 blasts or primary mesodlasts, which bud forth the mesoblast-bands, cell by cell; /. lateral teloblasts, 

 comprising a neuroblast, nb, from which the ventral nerve-cord arises, and two nephrob lasts, n, of 

 somewhat doubtful nature, but probably concerned in the formation of the nephridia. C. Lateral 

 group of teloblasts, more enlarged, the neuroblast, nb, in division ; n. the nephroblasts. D. The 

 primary mesoblasts enlarged; one in division. 



figure results in an equal division ; an eccentric position caused by a 

 radial movement of the mitotic figure, in the direction of its axis 

 toward the periphery, leads to unequal division, and the greater the 



