546 LIFE-HISTORIES 
Fic. 375.—Selaginellas. Germination of microspores. A-—E, different views 
of the spore showing the prothallus-cell (p), cells of the antheridium- 
wall (w), and the cell producing spermatozoids (s), *#2. In # the cell- 
walls have dissolved previous to discharging the spermatozoids. F, 
spermatozoids, 7%. (Belajeff.) 
The spores begin to germinate while still within the sporangium. 
The contents of each microspore divides into several cells (Fig. 375, 
A-D) one of which (p) represents the vegetative part of a male 
gametophyte, the others constituting a male gametangium, in the 
center of which is formed a cluster of elongated gametes closely 
resembling the male gametes of a liverwort. After leaving the 
sporangium the microspores liberate their motile gametes by rup- 
ture of the wall. The large cell which constitutes the macrospore 
is rich in reserve food and begins to germinate by dividing into a 
number of small cells within the wall. Soon the macrospores are 
set free from the sporangium, and continue to germinate by forming 
a few archegonia on the upper side, which eventually protrudes from 
the ruptured spore-wall shown in Fig. 376. After fertilization, the 
ege-cell divides into an upper and a lower half, the lower half grow- 
ing into an embryo, while the upper half develops into a peculiar 
organ called the suspensor (et). This by its elongation pushes the 
embryo, foot foremost, into the mass of vegetative cells upon which 
it feeds. The root and the shoot of the young embryo (Fig. 377) 
finally protrude from the macrospore, the foot (f) still remaining 
within as an organ of absorption in contact with the food supply. 
There are two cotyledons, which, containing chlorophyll, soon begin 
to make food for the plantlet, and aided by the developing leaves of 
the plumule, finally render the young plant self-supporting. From 
the upper side of each cotyledon (and often on later leaves) a flat 
