NUTRITION AND SEASONAL LIFE OF PLANTS 129 



made from sugar in small quantities by the general cell cyto- 

 plasm. When the seeds are fully formed and stored with food, 

 they are shed from the mother plant and begin their long winter 

 rest preparatory to starting the new bean plant of the next 

 season. When winter comes on, the living substance of the 

 plant body is killed by frost, and the cellulose framework falls to 

 the ground and is gradually converted into carbon dioxide and 



Inflorescence 



Seed (winter rest) 

 Adult plant 

 FIG. 64. The seasonal history of the annual bean plant 



Spring Seedling 



germination growth 



water by fungi and by bacterial ferments. The seeds, meanwhile, 

 are furnished with resistant seed coats and rest safely upon or 

 in the soil until the next spring, when they germinate and pro- 

 duce a new generation of bean plants. 



Assimilation. The conversion of food into living protoplasm 

 is constantly taking place as the bean plant grows and pro- 

 duces new organs and tissues. This conversion of food into 

 living protoplasm is called assimilation. A considerable bulk of 

 cellulose in the form of- new cell walls is also formed to serve 

 as the skeleton, or framework, for the mechanical support of the 

 living substance of the plant body. 



