CHAPTER II. 
PLANT STRUCTURE AND GROWTH. 
ALL plants commence existence as a single cell, like 
Torula or Protococcus, and it is only by the multi- 
plication of these cells, the alteration of their form 
by pressure against each other, and their development 
into tubes, &c., that we get the wonderfully varied 
and beautiful forms of higher plant life. As we have 
seen, the lowest forms of plants are wuzcellular, but 
from these to the complex organisation of the forest 
trees there is a very gradual advance. In,the same 
sroup as Protococcus—the Alge—we have piants with 
a larger number of cells, as Zyguema and Osczllatoria. 
In the division of Fungi we have a similar advance 
from the simple form of Zoruda, through the moulds 
with strings of cells placed end to end, up to the 
mushrooms and toadstools. From the remarks in 
the previous chapter, it will be seen that plants are 
divided into two great groups, those that possess 
chlorophyll—green plants—and those that do not— 
fungi. 
The green plants are again broken up into other 
divisions, according to the complexity of their organ- 
isation. 
In Zygnema we have seen how the normal form 
