87 



place. This is affected in such a way that the members of the bivalent 

 are separated and one member passes entire to each daughter nucleus, 

 thus bringing about a qualitative division. The retreating chromosomes 

 undergo longitudinal fission as they pass to the poles. Having arrived at 

 the poles, they soon break up into smaller pieces, lose entirely their iden- 

 tity and form a complete resting nucleus. This condition lasts but a short 

 time when a spirem is again formed which segments into rod shaped 

 univalent segments. These segments have been quite generally assumed to 

 be identical with the ones which appeared at the poles of the spindle at 

 the close of the first mitosis, but since these segments were seen to lose 

 their identity entirely tliere is no basis in fact for such a supposition. 

 If these segments are not identical witli the grand daughter segments of 

 the first mitosis then this division is not equational. The first division 

 in both genera is (lualitative and reductional ; the second may be conceived 

 either as equational or qualitative. 



The investigations on which rliis preliminary report is based will ap- 

 pear later in a more complete form, together with figures illustrating the 

 entire process of mitosis. 



