THE CELL AND ITS CONTENTS 15 
are also to be seen stores that will go to the building 
up of future protoplasm, and these are called aleurone- 
grains. These are chiefly to be found in seeds. With 
them may also be sometimes seen little round bodies 
called globoids, which consist of double phosphates of 
lime and magnesia. 
In a few cells one also finds mineral crystals, whose 
use or value is unknown. A probable suggestion is that 
these crystals are just a convenient form of rubbish heap 
for materials which the plant has taken up from the 
earth, and for which it has no use. 
Before we consider the factory at work we must try to 
understand some of the more complicated structures into 
which cells develop in the higher plants. Seaweeds, 
funguses, and mosses are content with the cells alone, 
but the ferns and the flowering plants begin to build 
up that arrangement of vessels and fibres, or jibro- 
vascular system, which I roughly likened above to our 
own skeleton. 
