BRYOPHYTES 
307 
After the spores are formed the walls of the mother 
cells disorganize, and the spores are left lying loose in 
a cavity which was formerly occupied by the sporogenous 
tissue. All mother cells do not always organize spores. 
In some cases some of them are used up in supplying nour- 
ishment to those which form spores. In other cases, certain 
mother cells become much modified in form, being organ- 
ized into elongated, spirally-banded cells called elaters (Fig. 
286), meaning "drivers" or "hurlers." These elaters lie 
among the loose ripe spores, are discharged with them, and 
by their jerking movements assist in scattering them. 
The sporogonium is a very important structure from 
the standpoint of evolution, for it represents the conspicu- 
ous part of the higher plants. The " fern plant," and 
the herbs, shrubs, and trees among " flowering plants," 
correspond to the sporogonium of Bryophytes, and not to 
the leafy branch (gametophore) or " moss plant." 
