38 



NORMAL HISTOLOGY. 



with its apices at the polar bodies and its equator coincident with 

 that of the cell and the plane of the monaster. 



It is along the lines of this spindle that the chromosomes travel 

 toward the centres of the attraction-spheres occupied by the polar 

 bodies. 



The phases of karyokinesis that follow metakinesis are similar to 

 those that preceded it, but occur in inverse order. 



4. The Diaster Phase (Fig. 13). The chromosomes, having 

 reached the attraction-spheres, group themselves around the polar 

 body to form a wreath on a plane perpendicular to the axis joining 

 the poles. These wreaths, with the achromatic spindle, have an 

 appearance somewhat resembling the letter H, with a long cross- 

 piece, formed by the spindle, remaining uncolo^ed or only faintly 

 tinged by nuclear dyes, while the uprights, made up of the chromo- 

 somes, are deeply stained. 



The ends of the chromosomes now unite to form a thread, and 

 the wreath-like arrangement gradually passes into that of the 

 dispirem. 



5. Dispirem (Figs. 14 and 17). The halves of the original chro- 

 moplasm of the nucleus are now arranged in two skeins about the 

 poles. From these the two daughter-nuclei of the future cells are 

 formed (Fig. 18). 



FIG. 17. 



FIG. 18. 



Fig. 17. Dispirem. In this case the polar bodies have not divided (compare Fig. 16). 



Fig. 18. Daughter-nuclei which have nearly reached their full development. Centrosomes 



present in the cytoplasm. 

 In these figures the structure of the cytoplasm is not given. 



During metakinesis the cytoplasm of the cell begins to show 

 signs of division. This may be accomplished through a constric- 

 tion of the body of the cell, which gradually becomes deeper and 

 finally severs the two portions ; or a series of punctiform or short 



