No. 24 Effert of 0-57 millimolar aminopterln on a cell in prophase, (o) 7 minutes 

 after addition. Nucleoli have just disappeared, (fa) 9 minutes after addition. The 

 chromosomes are contracting, (cj Fixation after 37 minutes. The chromosomes are 

 tightly clumped. 



Ao. 25 Effect of 065 millimolar chloracetophenone on a cell in prophase, (o) i 

 minute after addition. Nucleoli still present, (fa) 5 minutes after addition. Nucleoli 

 have just disappeared, (c) Fixation after 17 minutes. 



