124 THE VEGETATIVE FUNCTIONS OF PLANTS 
vided for in many ways. Young embryo plants in the 
seed find a rich supply of nourishment, ready made by the 
parent plant, stored within their tissues (as in the bean 
or pea), or around them (as in the corn, or castor-oil seed, 
Fig. 83). They do not have to manufacture their own 
food at first. Young and rapidly growing plants (seed- 
lings and young saplings) have much larger leaves than 
mature plants of the same species (Fig. 55). On this 
account food making, from the raw materials taken in 
by the plant, may proceed much more rapidly. Plants 
commonly store food in quantity where it will be needed 
in the future by rapidly growing new parts, and such 
storage organs usually become swollen by the abundance 
of stored food. This is illustrated by "potatoes," which, 
as is well known, are underground branches (tubers) stored 
with food for the use of young sprouts when they begin 
to grow in the spring. All bulbs are to be interpreted in 
the same way. Farmers recognize the need on the part 
of growing plants for an abundance of food, when they 
fertilize their fields, thereby placing in the soil a rich 
supply of the raw materials out of which the growing 
crops can manufacture food to meet their needs. 
