1915] HUTCHINSOX— ABIES BALSAMEA 463 



the second set of spindle fibers begins to be differentiated, the 4X 

 number of chromosomes are indiscriminately intermingled (figs. 

 46-48). Half the number pass to each pole to form the daughter 

 nuclei. 



The chromosome count. — Repeated chromosome counts in the 

 sporophyte and gametophyte confirm one another in fixing the x 

 and 2X numbers for Abies balsamea as 16 and 32. The individual 

 chromosomes which appear during the prophase of the division in 

 the central cell are shown in figs. 8 and 9. The count is 16. The 

 division of the body cell in anaphase gives 39 segments. A recon- 

 struction of parts separated by the microtome knife results in a 

 count of 32, or 16 passing to each pole. At the time of approxima- 

 tion of the chromosomes in the egg, there are 16 pairs (figs. 29-33). 

 When segmentation takes place, 32 pairs of segments are present 

 (figs. 34-40). In the nucleus represented in figs. 43-45, there are 

 72 chromosome pieces; figs. 46-48 show 63 almost complete 

 chromosomes, besides a number of ends. Undoubtedly we have 

 in each case the 4.V number, or 64 chromosomes. 



The daughter nuclei. — During telophase the chromatin strands 

 remain remarkably distinct (figs. 49-52). They elongate greatly, 

 and become irregularly looped (figs. 50, 52). It would seem that 

 each is in contact with the periphery somewhere throughout its 

 length. Contraction is followed by an increase in the size of the 

 nuclear space; the latter is accompanied by a vacuolization of the 

 chromatin (fig. 55). The nuclear outline is still lobed, the lobes 

 corresponding to the loops of chromatin. The nuclear membrane 

 forms late. As the nucleus continues to enlarge, the chromatin 

 becomes still more discontinuous, but the outline of the strands 

 may still be readily traced. 



It is to be noted that of all the material which was inclosed by 

 the membrane of the egg nucleus, only the chromatin is included 

 in the newly organized daughter nuclei. The large vacuolate 

 darkly staining bodies, the filaments pervaded by granules, and 

 the fibers are all excluded when the membranes inclose the daughter 

 nuclei. We may conclude that these materials, although they may 

 be found within the nuclear membrane, are not essentially nuclear 

 and are not directly concerned in mitosis. They are, at most, 



