128 



III. By reference to Figs, i and 2, it will be seen that the water 

 content of the soil bears a more than usually close relation to the 

 rainfall. This may in part be accounted for by the fact that the 

 subsoil is only from twelve to eighteen inches below the surface 

 and is a hardpan almost impervious to water. The drainage 

 is therefore poor. Moreover the structure of the soil is such 

 that a very few days of dry weather causes a rapid decrease in 

 its water content. 



Table 



III. 



Rainfall at College Station, 



Texas 



Year Nov. i 



to May 31, Inches] June i to Oct 31, Inches 



Total, Inches 



1912-1913 

 1913-1914 

 1914-1915 



22.50 7.92 

 38.20 10.93 

 30.20 17.07 



30.42 

 49-13 

 47.27 



From Table IV it appears that during the time of observation 

 there were two periods of high water content and two of low in 

 these soils. 



Table IV. Water Content of Soil Samples by Periods 



Period 



Maximum 

 Per Cent 



Date 



Minimum 

 Per Cent 



Date 



Mean 



Dec. 6 to Mar. 22 

 Mar. 22 to Apr. 18 

 Apr. 18 to May 19 

 May 19 to May 30 



26.47 Dec. 23 

 8.86 1 Apr. 3 



25.63 Apr. 24 

 7.80 May 22 



10.26 

 6.52 



10.55 

 3.82 



Mar. 22 

 Mar. 28 

 May 19 

 May 29 



18.53 

 7-33 



18.45 

 6. 28 



The young Droseras appeared about the middle of the first 

 period of high-water content and disappeared shortly after the 

 beginning of the last period of low-water content. However, 

 on March 30, the plants in the upper portion of the field were 

 found to be dying. Upon examination the first two inches of 

 soil of this part showed a water content of 3.46 per cent, as com- 

 pared with 6.47 per cent in samples of like depth from localities 

 in which the plants were still growing. The plants grew vigor- 

 ously in all places having a water content of 6 per cent or more 

 during the period from March 24 to April 18. The rosettes of 

 leaves reached a maximum size in most of the plants and the 

 scapes attained a height of one centimeter or more. The first 

 blossoms appeared about April 30. 



