198 



BOTANICAL GAZETTE 



[march 



averaging at least 50 per cent above the normal. There was no 

 actual drought at any time during the season, but there were two 

 rather dry periods, June 14- July 6 and July 11-25, ^^ which light 

 rains gave totals of o. 20 and o . 09 inch respectively. 



When the subsoil at Akron, even in that unusually wet summer, 

 had its moisture content reduced to such a low point, it is probable 



TABLE IX 



Data from 6 individual borings on the H. O. Ranch, November 22, 1907, 

 illustrating variations from boring to boring 



Depth 



No. I 



Mini- 

 mum 



Foot 



HYGROSCOPIC COEFFICIENTS 



I 



2 



3 



4 



5 



6...- 



7 



Average 1-7 



I 



2 



3 



4 



S 



6 



7 



Average 1-7 



6.1 



6.7 

 6.7 



4.2 



5-3 



5-2 



6.3 



1.6 



1 .1 

 1 .1 

 I.I 



1.2 



1-3 



I .2 



1-3 



that in a really dry season the ratios would be found as low as 

 those we encountered in southwestern Nebraska. 



The root systems of the native plants were studied by Shantz, 

 but the penetration of the grama and buffalo grasses he indicates 

 (10) would not account for the removal of available moisture from 

 below the first foot or two. 



Burr (7) reports data from a prairie sampled in the spring, 

 summer, and early autumn of 191 2 (table X). In the spring high 

 ratios were shown in the first 2-3 ft., but by the end of June the 



