Studies on Chromosomes. 



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Figure 4. 



Banasa calva. — a, b, Metaphase-figures, first division, in polar view, showing fifteen chromosomes, 

 including two small ones {h, heterotropic chromosome, /', small idiochromosome — the large idiochro- 

 mosome not distinguishable); c-g, successive stages of first division, in side-view, showing division of 

 the small idiochromosome (;'), and the unipolar movement of the heterotropic chromosome {h); k, meta- 

 phase-group of second division, with thirteen chromosomes; /, metaphase-group of the same division 

 with fourteen chromosomes; j-l, metaphase and early anaphase of second division, showing separation 

 of the idiochromosomes, and equal division of the heterotropic chromosome; m, sister-groups from the 

 same spindle, early anaphase second division, fourteen-chromosome type; n, similar pair, late anaphase; 

 0, similar pair, middle anaphase, thirteen-chromosome type; p, q, entire chromosome-group from a 

 single nucleus at the end of the growth-period, showing idiochromosome-dyad (;') and heterotropic 

 chromosome {h). 



