326 BOTANICAL GAZETTE [MAY 
cytoplasm at the same time becomes highly granular (jigs. 
40, 41). 
Another peculiarity of the microspores is the frequent occur- 
rence of a division of the tube nucleus ( figs. gz, 47a). Itis 
impossible to regard either of the large nuclei of fig. 47 as 
a sister of the generative nucleus. The latter is set apart 
within a separate cell quite early in the history of the micro- 
spore, and keeps a constant outline and appearance whether or 
not the third nucleus is present. Furthermore, the two free 
nuclei are too large to be so explained, and are alike in every 
particular, having all the characters by which the tube nucleus is 
usually distinguishable. Each has a prominent nucleolus, and 
shows an erythrophilous reaction in staining with haematoxylin 
and erythrosin, while the generative nucleus has no nucleolus, 
very abundant chromatin, and cyanophilous staining. 
So far as I know, a division of the tube nucleus has been 
recorded only by Dr. Chamberlain? of this laboratory in the case 
of Lilum Philadelphicum, where its occurrence is rare. In 
Eichhornia, however, fully half of the mature pollen grains aa. 
ined exhibit this peculiarity. The fate of these tube nuclei, and 
whether or not there is a division of the generative cell in the 
pollen tube, I did not succeed in determining. In longitudinal 
sections through the style pollen tubes were easily seen ee 
three central canals, but almost always they showed marks of ee 
integration. Since Eichhornia does not set seed in our latitu . 
and there are apparently no abnormal structures in the a 
sac, it is probable that the division of the tube nucleus exe to 
pathological conditions in the pollen grains, and the failure 
produce seed should be ascribed to the same cause 
MEGASPORES. 
dy fused 
The youngest flowers obtained had the mia two 
in such a way as to contain three loculi, and in eac These ridges 
longitudinal ridges run along the central axis. ie time 
are the six placente. The only sign of the ovules 
: + 423-430 1897 
* Life history of Lilium Philadelphicum. Bor. Gaz. 23 2423-430 189 
