i 9 isl HUTCHINSON— MALE GAMETOPHYTE OF PICEA 293 



to osmosis. Moreover, the increase in size is most rapid when the 

 nucleus is surrounded by most cytoplasm; the primary nucleus 

 soon regains the size characteristic of the resting stage (figs. 6, 9, 

 18, 20, 21). 



Chromatic structures 



The resting nucleus contains several nucleoli. In early pro- 

 phase "condensing bands" and "zig-zag threads" of chromatin 

 become differentiated; definite looped chromosomes are formed 

 (figs. 15, 35). Only in rare cases could their double nature be seen 

 at this stage; it would seem that the halves remain rather closely 

 appressed until metaphase. The nucleoli are present until late 

 prophase (figs. 16, 35, 48). The chromosomes contract before 

 aggregating in a definite cell plate (figs. 16, 48); during anaphase 

 they are characteristically V-shaped (figs. 2, 3, 17). In early 

 telophase compact chromatic aggregations are formed (figs. 4, 18, 

 41, 47, 49). These soon become irregularly vacuolate, and as the 

 vacuoles increase in size, anastomosed bands of chromatin become 

 differentiated (figs. 5, 22, 24, 43). The process is similar to that 

 described by Sharp (8) in Vicia. The bands become more irregular 

 in outline, and a number of nucleoli appear (figs. 23, 25, 44). As 

 the number of nucleoli decreases, they become individually larger 

 (figs. 20, 45, 6, 8, 46, 48, 50). The irregular bands are replaced 

 by zig-zag threads and the nucleus passes again into the resting 

 condition. 



Achromatic structures 



The achromatic structures in all primary divisions are most 

 characteristic. The spindle fibers are inconspicuous during ana- 

 phase (figs. 2, 3, 36, 42); in many cases they can be distinguished 

 only with difficulty (fig. 17) and are only slightly more definite 

 than the vague radiations in the polar cytoplasm (figs. 3, 36). In 

 early telophase there are very definite strands between the daughter 

 nuclei. These are arranged in the form of a hollow cylinder (figs. 

 4, 18) which gradually broadens (figs. 19, 43) and moves toward 

 the pole, partly enclosing the antheridial nucleus (figs. 5, 21, 24). 

 Usually the fibers come in contact with the cell wall, the free 

 ends swing outward, and so remain as curved or radiating strands 



