12 Q6 PHYSIOLOGY 



(3) Anaphase (the travelling of each half -chromosome to the extremity 

 of the spindle). 



(4) Tekphase (the retrogressive changes leading to the conversion of 



FIG. 555. Diagram showing the changes which occur in the centrosomes 



and nucleus of a cell in the process of mitotic division. (Sen A FEB.) 



The nucleus is supposed to have four chromosomes. 



the chromatin filaments into an ordinary resting nucleus, which are accom- 

 panied or preceded by a division of the cytoplasm across the equatorial part 

 of the spindle). 



When the spireme has broken up into separate chromatin loops, it is 

 possible to count them, and it is found that the number present in any cell 

 is constant for the species. Thus every human somatic cell has sixteen 



