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Heredity and Environment 







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Fig. 8. Successive Stages of Mitosis in the Cleavage of the Egg of 

 a Fish (Fundulus) showing that new chromosomes are formed inside of 

 old ones (chromosomal vesicles), that chromosomes or chromosomal 

 vesicles persist from one division to the next and that even the "resting" 

 nucleus is composed of chromosomal vesicles. A, nucleus at beginning of 

 mitosis, having shrunk from dotted outline and showing chromosomal 

 vesicles containing chromatin granules ; B, each chromosomal vesicle con- 

 tains granules or chromomeres which are condensing to form a chromo- 

 some ; C, amphiaster showing faint outlines of the chromosomal vesicles 

 with their contained chromosomes ; D, amphiaster showing each chromo- 



