116 THE STORY OF LIFE'S MECHANISM. 



which give it a starlike appearance, or, more 

 commonly, the appearance of a double star, since 

 there are two centrosomes close together (Fig. 28). 

 These radiating fibres, whether arising from the 

 centrosomes or not, certainly all centre in these 

 bodies, a fact which indicates that the centro- 

 somes contain the forces which regulate their 

 appearance. Between the two stars or asters a 

 set of fibres can be seen running from one to 

 the other (Fig. 29). These two asters and the 



FIG. 29. FIG. 30. 



FIG. 29. The centrosomes are separating but are connected by fibres. 

 FIG. 30. The centrosomes are separate and the equatorial plate of 

 chromosomes, cr, is between them. 



centrosomes within them have been spoken of as 

 the dynamic centre of the cell since they appear 

 to control the forces which lead to cell division. 

 In all the changes which follow these asters lead 

 the way. The two asters, with their centro- 

 somes, now move away from each other, always 

 connected by the spindle fibres, and finally come 

 to lie on opposite sides of the nucleus (Figs. 

 29, 30). When they reach this position they are 

 still surrounded by the radiating fibres, and con- 



