STEUCTUEE AND WOEK OF PLANTS 



17 



Sugar and starch may be used as food by the plant, being 

 transported to and made into the living parts of the plant. 

 Or these things may be made [^ 

 into more complex foods, (Vpt 

 known as the proteins, by Irhf 

 the addition of some of the 

 compounds of nitrogen, potassium, 

 phosphorus, or other substances, 

 and then digested and used by the 

 plant. Replenishment and growth 

 of new parts can take place only 

 by means of foods, and since the 

 plant makes its own supply, the 

 importance of the process is very 

 great. 



Manufactured foods are carried 

 to all the living parts of the plant. 

 They may also be stored in almost 

 any plant structure. When in proc- 

 ess of moving through the plant, 

 these foods are believed to pass 

 through the soft portions of the 

 fibrovascular bundles. 



Furthermore, often more food is 

 made by green plants than they FIG. 12. Apparatus for collect- 

 need at the time, or even, in case ing oxygen from working plants 

 of some plants, than they ever use, "SSSSSSlSSffSt 



and this is Stored most Commonly uate. Bubbles of oxygen pass 



in the form of starch, though some- u P ward f 5 Qm th f cu * ends of f e 



& stems and crowd out some water 



times in Other forms. This Stored from the previously filled grad- 



food may be USed later by the uate. The ordinary test for oxy- 



J J gen with a burning stick will 



plant, Or as food for men and Other determine whether it is present. 



animals. It may also be moved by In such an experiment care must 



_ . * , J be taken to see that there is 



the plant and stored in a different plenty of space about the collect- 

 structure from that in which it was in s tube to 5f it * re * pass f ge 



of the gases that are m the water, 

 first located. After Ganong 



