PLANTS. 47 



well-developed ears. When it is sowed as thick as 

 wheat or oats, although no other plants grow with it, 

 it will attain a height of but three or four feet, with 

 but the indication of ears and no seeds at all on 

 them. 



Plants require space in proportion to the size of 

 the full-grown individuals. Large plants require 

 much space, and small plants require little space. 

 Thus clover, timothy and field peas are planted 

 but a few inches apart because the full-grown 

 plants are small and require little food and light. 

 These plants, too, when started to grow in soil in 

 wfiich all weeds have previously been destroyed, 

 so take possession that no weeds are allowed to 

 grow. The reason for this is that most of the air 

 and light are shut out. As soon as the ripened 

 crop is removed, thousands of weeds spring up, 

 showing that the seeds were there waiting for an 

 opportunity to germinate. 



Plants cannot be considered as having the power 

 to reason, yet they spend no energy in germinating 

 when the conditions are such that growth would be 

 impossible. They behave in many other ways just 

 as wonderful as this. 



STRUCTURE OF PLANTS. 



Like animals, plants are either simple or complex 

 in structure. A simple organism is one in which 

 the life processes are carried on in a single cell, or 

 a few united cells. A good example of a cell is the 



