'Facts and Factors of Development 



19 



sizes, come out of a nucleus at the time of division as went into 

 it at the preceding mitosis, each new chromosome coming out of a 

 chromosomal vesicle (Fig. 8, A\ B, C). Whenever one can trace 



FIG. 7. 



rise to a spindle (a) with astral radiations at its poles; F, Middle stage 

 of division in which the chromosomes lie in the equator of the spindle 

 forming. the equatorial plate (ep) ; G, H, Stages showing the splitting of 

 each chromosome and the movement of the halves toward the poles of 

 the spindle; ep, Equatorial plate; if, Interzonal filaments; n, Nucleolus: 

 I, Complete separation of daughter chromosomes and formation of daugh- 

 ter nuclei; beginning of division of cell body; /, Complete separation of 

 daughter cells and return of nucleus and centrosome to resting condi- 

 tion. (After Wilson.) 



