THE ‘NON-CELLULAR’ TYPE 49 
produce new ones by the rapid division of 
the cells in the region between the stalk and 
the base of the expanded frond. 
CHAPTER V 
THE ‘** NON-CELLULAR”’ TYPE OF 
ORGANISATION 
In the series of plants hitherto considered 
we have been mainly concerned in tracing 
certain lines of evolution in form and structure, 
accompanied by a corresponding differentia- 
tion and specialisation, amongst the cells of 
which the bodies of the plants are constructed. 
These culminate in such forms as the higher 
red and brown seaweeds in which the char- 
acter of leafy plants is very closely imitated, 
save in one important respect. The terrestrial 
plant, unlike the submerged seaweed, is 
exposed to difficulties connected with the 
water supply, and, as we shall subsequently 
see, this has necessitated structural and other 
developments far in advance of those ex- 
hibited by aquatic plants. Indeed, a high 
D 
