REPRODUCTION 97 



portion which is situated at the centre of the 

 cell. 



All these events may be considered as having 

 been preparatory to the great business of divi- 

 sion which is now to take place. The chromatin 

 masses, at the centre of the spindle, now be- 

 come divided into two parts, each by a line of 

 fission which is at right angles to the long axis 

 of the spindle. Two groups of chromosomes' 

 are thus formed which we may roughly speak 

 of as a right and a left group. Each of these 

 now retreats farther and farther from the 

 centre and from its sister group and ap- 

 proaches nearer and nearer to the periphery 

 and to the centrosome. 



It does not, however, actually reach this 

 structure but stops short on arriving near it, 

 so that we now find on either side of the cell 

 a group of chromosomes situated to the inner 

 side of the centrosome, which chromosomes as 

 they take up this position become shorter and 

 thicker and crowd up close to one another. A 

 wall forms around each group of chromosomes, 

 a new nucleus or pair of nuclei being thus 

 constituted, and finally a wall of separation 

 divides the two parts of the cell from one 

 another and the process of division is complete, 

 for where one cell alone existed there are now 

 two. Such a process of division, accompanied 



G 



