18 



THE INDIVIDUAL ORGANISM 



Prophase. This is the first stage of mitosis and the one of longest 

 duration. As it begins, the chromatin material of the nucleus becomes 

 more stainable and can now be seen to comprise a number of separate and 

 distinct chromosomes. At this stage each chromosome is in the form of a 



centrioles 



centromere 



chromosome 

 showing sister 

 chromatids 



spindle 



equatoria, 

 plate 



Mid Prophase 



centriolei 



moving 



opart 



Late Prophase 



Metaphase 



Anaphase 



' late Anaphase 



8. Telophase 



9. Daughter cells in. 



resting stage 



Fig. 2.2. Successive stages in the mitosis of an animal cell. 



long, exceedingly slender double thread. The two threads (sister chroma- 

 tids) of each chromosome are identical or mirror images of one another, lie 

 close together, and are connected at a single point by a minute structure 

 known as the centromere. 



