40 



THE ECOLOGICAL RELATIONS OF ROOTS. 



holding capacity of 50 or 60 per cent of its dry weight. By the action 

 of water and especially of the prevaihng southwest wind, the prairie 

 topography has been molded into rounded hills which reach a height 

 of 100 to 360 feet and resemble sand-dunes. The soil is usually many 



Table 8. 



Table 9. 



Southwest Slope. 



