IV] 



STRUCTURE OF THE CELL 



175 



(Fig. 50). They fuse together and form once more an alveolar reti- 

 culum and may occasionally at this stage form another spireme. 



central spindie 



manHe-fii\ 



cplit chrcmosomc 2 



Fig. 48. 



Fis. 49. 



A boundary or surface wall is now developed round each recon- 

 structed nuclear mass, and the spindle-fibres disappear (Fig. 51). 

 The centrosome remains, as a rule, outside the nucleus. 



7. On the central spindle, in the position of the equatorial 

 plate, there has appeared during the migration of the chromosomes, 

 a "cell-plate" of deeply staining thickenings (Figs. 50, 51). This 

 is more conspicuous in plant-cells. 



