THE TREE GERM. 25 
Dicotyledons. It would be going beyond the 
scope of the present volume to discuss the dis- 
tinction further, except to remark that these 
divisions of flowering plants—amongst which, of 
course, Trees are included—usually represent dis- 
tinct kinds of structure and distinct methods of 
growth. 
The size and form of the cotyledons in the di- 
cotyledonous plants, which include nearly all 
our woodland Trees, are greatly varied. They are 
usually roundish bodies, are sometimes thick and 
fleshy, as in the acorn and in the chestnut; some- 
times thin, as in the Maple seed, and at other 
times crumpled or folded. Their purpose is to 
furnish—if we may borrow an expressive term 
from the science of mechanics—a sort of fulerum 
to the plant in its earliest stage. Between the 
twin cotyledons is placed a small variously-shaped 
but usually cylindrical body consisting of two 
parts, united to each other end to end, the plumule 
and the radicle, which are, as we have seen, the 
one the germ of the future stem, the other the 
germ of the future root. The root end, destined 
to grow downwards and develope into the perfect 
c 2 
