354 BOTANICAL GAZETTE [NOVEMBER 
The cell plate is soon deposited, and divides the generative 
cell into two parts. The two daughter cells do not separate, 
but. remain connected as a two-celled body during their entire 
stay in the spore. A more or less prominent constriction often 
occurs at the middle, but this does not seem to be constant 
(fig. 44). The pollen grain is always somewhat flattened, and 
since the generative nucleus is usually adjacent to the flat side, 
it is not possible to tell whether the latter remains attached to 
the wall after division. The difficulty was increased since the 
pollen escapes from the anther very soon after the second 
division. 
An examination of the literature relating to the pollen grain 
of the monocotyledons furnishes some interesting facts. Stras- 
burger found the division of the generative cell to take place 
within the spore only in Juncus and Arum; while in all other 
cases the division was in the tube. All these cases belong 
either to the Liliaceew, Orchidacee, Amaryllidacee, or Iridacez. 
Schaffner found the division occurring in the spores of Typha, 
Alisma, and Sagittaria,?7 and Campbell found the same to be the 
case in Naias, while the writer finds the same phenomena ' 
Acorus and Potamogeton. In all cases among the monocotyle- 
dons, where division occurs in the pollen grain, with the — 
tion of Alisma and Sagittaria, the generative cell is - vai 
enclosed by a wall, and always becomes two-celled after cen 
although Campbell claims that the two cells in Naias Ga 
before passing into the tube. Schaffner was not able to sees : 
any walls around the generative cell in the two above a oe 
species. From this it appears that the division of the et 
nucleus in the tube is mostly confined to the ee 
orchidaceous groups among the monocotyledons, while t os 
sion within the spore characterizes the spadiceous and 0 
ceous groups. 
*° Befruchtungsvorginge bei den Phanerogamen 22. 1884. 
77 A contribution to the life history of Seg#tlaria variabilis. BOT: 
1897. 
