538 



CELL MECHANICS 



chromosomes, share their differentiation and hence their homology. 

 There is no reason to doubt that they are all equivalent in structure 

 where they are equivalent in behaviour and that they have a common 

 origin as well as a common function (Muller and Painter, 1932, D., 



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 hhase 



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Fig. 155. — The division cycle of the centromere at mitosis and 

 meiosis. Univalents at meiosis vary between the mitotic 

 and meiotic cycles. (D., 1935 g) 



1933, Agapanthus). The differences in their movement at anaphase 

 and in the condensation of special chromosomes at prophase may, 

 however, depend on differences in their structure [v. infra). 



The centrosomes and chromosomes both divide between mitoses. 

 We have already noted some evidence of the time of division of the 

 centromere. Undoubtedly it has divided at the mitotic anaphase. 

 Most observations agree that it is undivided at the first meiotic 



