THE BRAIN OF THE EARTH 



for the production of crops of sorghum, cotton, 

 flax and sugar-beets. 



"Medium grass and grain soils, thirty per 

 cent each, fine sand, silt and clay. 



"Wheat soils, varying from twenty to thirty 

 per cent of sand, twenty to thirty per cent of 

 clay, fifty to seventy-five per cent of silt." 



But the soil is something more than mere 

 earth. It is the home of unthinkable myriads 

 of living beings, vast, uncountable colonies of 

 life. It is low life in its order, to be sure, but 

 it is as truly life as the life of the most highly 

 organized scientist who works amidst its 

 mysteries. 



In the burning of the pinch of rich soil 

 upon the platinum scoop I did more than 

 merely to destroy the dark humus, for in a mo- 

 ment's time I put to death more living things 

 than there are human beings upon the globe. 

 In a normal soil, not so rich or full of life as 

 this, more than one billion, six hundred million 

 bacteria have been found in a single gram. 

 They were infinitely minute, but they were 

 throbbing and pulsing with life when they 

 met death in the flames. 



These marvelous forms of life at work un- 



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