PART V 



THE WORK OF ROOTS AND STEMS 



I WHAT SOIL is MADE OF 



WE all know from early childhood that plants grow 

 out of the earth, for it is a fact constantly before our 

 eyes. But not everybody thinks seriously about what 

 he sees, and not everybody considers and wonders how a 

 plant thus comes ; what is in the ground to make it 

 grow ; why it should appear ; and why, having appeared, 

 it should continue to gain in size and height. 



People are so used to these marvels, so used to 

 having small plantlets push their way up through the 

 soil, and bring forth leaves and flowers and fruits, that 

 they take it all as a matter of course and forget to feel 

 any surprise. 



Yet it is by no means a matter of course ! 



Why should plants come up ? And why should they 

 increase in size? And why should they bear leaves 

 and flowers, and produce fruits ? If we did not know 

 that things are so, we should never have expected such 

 extraordinary happenings. For though they seem to 

 us quite ordinary, they would not be so to one who 

 had never before seen anything of the kind. 



What can there be in the soil which does so much? 

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