30 I The Process of Evolution 



Fig. 2.3. I Spiralization cycle of the chromosomes. A, interphase; B, C, 

 D, prophase changes, appearance of matrix; £, prometaphase, chroma- 

 tids visibly double; F, metaphase; G, anaphase; H, telophase changes 

 beginning in daughter chromosomes, disappearance of matrix. 

 {Adapted from De Robert is, Nowinski, and Saez, 1954, General 

 Cytology, 2d ed., W. B. Saunders Company. ) 



B 



D 



E 



G 



H 



