THE MECHANISM OF DEVELOPMENT 



149 



SECTION IV CELL DIVISION WITH AND WITHOUT 

 DIFFERENTIATION 



The accomplishment of this minutely accurate division of cer- 

 tain portions of the mother cell between the daughter cells at 

 division suggests two points : (i) that the matter thus carefully 



O 



II 



I J 



Fig. 21. Diagrams of the later phases of mitosis 



G, metaphase : splitting of the chromosomes (<?/) ; n, the cast-off nucleolus. //, anaphase : 

 the daughter chromosomes diverging, and between them the interzonal fibers (if), or 

 central spindle ; centrosomes already doubled in anticipation of the ensuing division. 

 7, late anaphase or telophase, showing division of the cell body, midbody at the equator 

 of the spindle, and beginning of reconstruction of the daughter nuclei. /, division com- 

 pleted. After Wilson 



divided is of special importance in shaping the activities of future 

 cells ; (2) that "daughter cells so provided should be identical, 

 and their after growth should not only be alike but should 



