PLANTS. 



59 



Growth from the Seed. From the seed first appears a 

 shoot, called the radicle, which extends downward into 

 the soil, and shortly afterward another shoot, called the 

 plumule, which seeks to find its way upward into the air 

 and sunlight. The radicle is the origin of 

 the roots of the plant, and the plumule the 

 origin of the stem, with its branches and 

 leaves. 



The reason why the root thus turns 

 downward and the stem upward is an un- 

 solved mystery. It cannot be due to any 

 attractive force of light upon the stem, or 

 any repelling force upon the root, as it has 

 been found that the same directions are 

 followed when a seed is sprouted in the air, 

 in absolute darkness. From this and from 

 other habits of plants, it would seem that 

 they are endowed with a kind of instinct, 

 similar to the instincts of animals. Some 

 plants always turn their leaves toward the 

 sunlight, while others turn them away. Germination of 

 Some flowers close in the afternoon and 

 open in the early morning. These facts ^aLL'fthe' coty. 

 we cannot account for with certainty, in l r d r ^^ lumulei 

 a scientific way, any more than we can ac- 

 count for the very principle of life which causes the seed 

 to begin to germinate and its growth to continue. 



Two Worlds for the Plant. A plant has two worlds, 

 or feeding grounds : the atmosphere above and the soil 

 beneath. One is as essential to the life and welfare of 

 the plant as the other. As plants cannot live when their 

 roots are withdrawn from the soil, so also most plants 

 will die if the portion above the surface is repeatedly cut 



