. 
372 BOTANICAL GAZETTE [JUNE 
sharply pointed and ends insmall centrosomes. After the daugh- 
ter star stage there are sometimes two bodies at each pole, which 
may represent divided centrosomes (fig.zo). The cells of the 
- bulb are often packed with starch. In some cases the starch is so 
abundant that the spindles are very much crowded by it (figs. 7z, 
z2). It will be seen from an examination of the figures that 
the development of the spindle proceeds as in the roots of Allium 
(30) and Pinus (12). It is never multipolar. This seems to be 
the normal course of division in vegetative cells, and represents 
the way in which the spindle is developed during the normal 
quantitative karyokinesis in the higher plants. 
Some time after the appearance of the Cytologische Studien, 
Némec, studying in the Bonn laboratory, announced that in 
vegetative cells the spindle is bipolar from the beginning. It is 
doubtful, however, whether the classification he made of bipolar 
and polycentric spindles will be found to hold good in general. 
THE MALE GAMETOPHYTE. 
The nucleus of the microspore probably divides early in the 
spring, for the pollen grain is well developed before the frost 
has left the ground. The tube nucleus takes a very light stain 
and is comparatively small, while the generative nucleus is large 
and is surrounded by dense-staining cytoplasm which is organ- 
ized into a cell amoeboid in form (figs. 76-78). These genera- 
tive cells are very striking in appearance. They can hardly 
have a cellulose wall because of the peculiar shapes they assume. 
The dense coat of cytoplasm is very different from that of Sagit- 
taria and Alisma, where there is very little cytoplasm, and it is 
difficult to see anything but the nucleus. 
Fig. 19 shows a germinated pollen grain on the stigma. The 
tube nucleus and generative cell are still side by side in the body 
of the grain, but are evidently preparing to pass into the tube. 
In the tip of the tube there is some dark-staining material which 
becomes very abundant as the tube elongates, forming dark 
masses or plugs (fig. 20). The tips of tubes in very favorable 
preparations showed no definite nuclei (fig. 27). They must be 



