42 



THE FOUNDATION 



Part I 



Fig. 3.9. Stages (metaphase and anaphase) in the mitosis of cells of a white fish 

 embryo. Microphotographs of stained and sectioned cells at an enlargement of 

 about 700 times. Note the lines of force that compose the spindle and radiate from 

 the centrosome in the metaphase, and the dimming of the spindle and the new 

 cell membranes in the anaphase. (Courtesy, General Biological Supply House, Inc., 

 Chicago.) 



the membrane separating the two new cells extends inward in a plane at right 

 angles to the spindle. In plant cells it starts from the center as a cell plate 

 and extends outward. 



Telophase (Reconstruction). The chromosomes in each nuclear group 

 uncoil and lengthen into knotted chromonemata. The spindle and at the same 

 time the rays about the centriole disappear. If two centrioles are characteristic 

 of the interphase each centriole now divides; if not, each one remains single. 

 The nucleolus becomes visible again and the boundary of the nucleus regains 



