BIOLOGY 



type represented in Figure 36, 

 is invariably four. 



G 



FIG. 36. DIAGRAM SHOWING THE 



SUCCESSIVE STAGES IN THE PROCESS 

 OF KARYOKINESIS 



A, the resting cell before it enters into the 

 process of cell division; H, the completed proc- 

 ess after the cell has divided into two parts; 

 ce, the centrosome; ch, the chromatin. For 

 description of the different stages, see text. 



spindle, known as the equatorial 

 chromosomes and the separation 



the number of chromosomes 



The second part of the 

 first stage consists of the 

 separation of the two gran- 

 ules of the centrosome as 

 shown at B. As these parts 

 separate, they are seen to 

 be connected by fibers form- 

 ing what is called the spin- 

 dle. The granules continue 

 to move away from each 

 other until they finally 

 come to lie at opposite 

 poles of the nucleus, form- 

 ing the amphiaster (Gr. am- 

 phi = both -f aster = star) 

 as shown at D. They are 

 still connected by the fibers 

 of the spindle, which now 

 pass into the nucleus itself; 

 the nuclear membrane in 

 the meantime has disap- 

 peared. At the end of this 

 phase the chromosomes 

 have assumed a position 

 midway between the two 

 granules, lying on the mid- 

 dle of the spindle, and at 

 right angles to the line con- 

 necting them, at E. They 

 thus form a sort of plate be- 

 tween the two poles of the 

 plate. The formation of the 

 of the centrosomes may take 



