418 VEGETABLE PHYSIOLOGY 
A feature of vegetative propagation which may here be 
emphasised is that the new individual is developed con- 
tinuously after its origination. There 
is no resting period, such as we find 
in most cases to mark the behaviour 
of the more specialised reproductive 
cells to be discussed below. 
Apart from cases of vegetative 
propagation of the individual, we meet 
Fie. 164 —Zoospore or With two other methods of reproduc- 
EES FRE tion, both of which involve the pre- 
paration of special cells set apart for this purpose. The 
first of these is characterised by the fact that each cell so 
produced is able to grow, either at 
once or after a short period of rest, 
into a new plant, which may or may 
not be exactly like the one from 
which the reproductive cell was 
formed. In plants exhibiting the 
simple organisation which we find 
among the seaweeds and the fungi, 
the parent and the offspring are in 
most cases precisely similar. The 
difference in this respect between 
them and plants higher in the scale 
will be discussed a little later. A 
good example of this mode of repro- 
duction, which was probably the primi- 
tive form, is afforded by the common 
ae sy se filamentous Alga Ulothriz. Any 
anor or dchlya _-—«d~PYOtoplast of the filament can divide 
4, closed ;2, ruptured, and into a number of separate pieces, 
allowing the zoogonidia : y 
- @ to exeape i ee each of ovoid shape with a pointed 
care at the zoogonidia end and furnished there with four 
; cilia (fig. 164). These new proto- 
plasts swim about for a time in the water, then come to 
rest, and after a time grow out into new filaments. Not 
