374 



CELL-DIVISION A. YD PEVELOPMENT 



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

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



fyir- 



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



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

 blasts or pri7?iary mesoblasts, which bud forth the mesoblast-bands, cell by cell; /. lateral teloblasts, 

 comprising a neuroblast, nb, from which the ventral nerve-cord arises, and two ncphroblasts, ti, 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; ;/. the nephrobiasts. 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 



