THE GREEN LEAF 57 
CHAPTER VI 
THE GREEN LEAF 
WE now pass from the study of the lower 
types of green plants to a consideration of the 
higher and more specialised forms of terrestrial 
vegetation. But if we restrict ourselves to 
a comparison of the vegetative organs of the 
more highly differentiated alge and of the 
higher plants, we shall be struck, not so much 
by the dissimilarities, as by the likenesses 
which exist between them. We meet with 
the same specialisation of the shoot into a 
stem bearing thin expanded structures— 
the leaves. There are the same organs for 
attaching the plant to rough surfaces, or 
anchoring it in a looser sub-stratum. It is 
not difficult to discern in the influence of light 
the common factor which has been chiefly 
concerned in the production of these resem- 
blances, so far at least as external form is 
concerned. 
But when we probe more deeply into the 
matter the real differences between the two 
classes of plants begin to make themselves 
apparent. They consist, so far as the vegeta- 
tive structure is concerned, in a specialisation 
of cells on the part of the land plant which 
may reach a grade of complexity almost 
