10 BOTANICAL GAZETTE [JANUARY 
appears to be simultaneous in the four spores of a given tetrad 
( fig. 53), though widely varying stages may be found within’a 
single sporangium. The spindle fibers in this division after the 
cell plate is laid down are much more prominent on the tube 
nucleus side (fig. 54). - The generative cell when first cut off 
along the wall of the spore is crescentic in outline, with a greatly 
elongated nucleus, but it soon becomes lenticular in form. 
Later, after its passage into the cytoplasm of the tube cell, it is 
for a time spherical (fig. 55); subsequently it becomes greatly 
elongated, and just before its division into the male cells is 
curved and may extend nearly across the spore ( fig. 57). 
The tube nucleus enlarges soon after its formation so as to 
become very conspicuous. It is at first spherical ( fig. 54), but 
a little later becomes amoeboid in shape and assumes the most 
varied forms, accompanied by a changed reaction to stains ( fig. 
56). Shortly before the division of the generative cell the tube 
nucleus regains its original form; with the organization of the 
male cells, however, it may again exhibit irregularities of out- 
line. Schaffner (13) in his studies of Erythronium found the gen- 
erative cell very large and displaying : such general activities as 
are here associated with the tube nucleus. 
The formation of the male cells seems to occur regularly long 
before the pollen grains are shed from the sporangium. The 
spindle formed within the long crescentic generative cell is itself 
slightly curved ( fig. 58), and the daughter nuclei retreat quite 
far apart before the partition is formed between them (/gs. 67, 
62). The male cells when first organized remain for some time 
end to end in the relation occupied at the time of their forma- 
tion, and thus continue the bow-shaped outline which character- 
ized the generative cell. Subsequently, with the symmetrical 
elongation of both male cells, their adjoined ends become long 
drawn out, yet still remain attached by their tips. This point of 
union acts like a hinge, permitting the cells to take the most 
varied positions with respect to one another, even swinging 
about so as to lie side by side ( figs. 63-66). In no observed 
instance did the male nuclei lie far enough apart to preclude the 
possibility of their cells being still united by these elongated 
