CELLS AND TISSUES ,,, 



centrioles move farther apart, the spindle fibers elongate, the n.icl.-ir 

 membrane disappears, some spindle fibers api)ear to attach to tlic 

 chromosomes, and gradually the longitudinally-split chromosomes 

 collect at the equator of the spindle. The next step in mitosis, known 

 as the metaphase, is the arrangement of the chromosc^mes. with each 

 split body on opposite sides of the equator of the spindle. Then the 

 two sets of chromosomes begin to move toward the opposite poles of 

 the spindle, the fibers which are attached to them getting shorter tunl 

 shorter. At this time comes the first external appearance of cell 



6enLrosphere 

 - (tentrosome 

 ^ chromatin 



spireme 



\nwi\ear- 

 fnamhrexna. 

 resting cell 



oCiso.ppeo.'ns 

 -spindle thread 



.CentroSome 



linVm - pi'ophase 



spireme sViortens 

 anoL thickens 



and of prophase 

 nuclecLr membi*ane 

 <A-isccppe<ir-s 



metxx-phaSe 



arjapbase 



end of anaphase 



te\ophasa 

 nuclear membranes 



ctoir^ter Cells 



restivxT stage. 



Mitosis in animal cells. Compare this diagram with that on page i 11. 



division, a slight constriction appearing in the cell body. The 

 constriction in the cell becomes more evident and, as the i)rocess 

 continues, the chromosomes become grouped so as to form the new- 

 nuclei of the two daughter cells. These progressive changes are 

 collectively known as the anaphase. In the final stage, or Idophasc, 

 the two sets of chromosomes gradually lo.-;e their individuality and 

 become Httle masses of chromatin grouped on linin fibers in the new 

 nuclei around which a nuclear membrane is formed. .Meantime the 

 constriction in the cell has gone far enougii to form two daughter cells, 

 the new separating partition appearing along the line nf the (-(luator 



