Seaver-Clark : Studies in Pyrophilous Fungi 119 



position after it had been acted on by the unheated-soil. The 

 results of our work on the quantitative relations of soil extracts 

 are presented in the following table : 



Increase of Soluble Matter in Soil upon Heating. 





Total solid 

 matter. 

 Per cent. 



Organic 

 matter. 

 Per cent. 



Inorganic 

 matter. 

 Per cent. 



New York soil ( i ) | 



Unheated-soil extract 

 Heated-soil extract 



0.036 

 0.138 



0.017 

 0.094 



0.019 

 0.044 



New York soil (2) |^ 



Unheated-soil extract 

 Heated-soil extract 



0.038 

 0.239 



0.022 

 0.179 



0.016 

 0.060 



Massachusetts soil ^ 



Unheated-soil extract 

 Heated-soil extract 



0.016 

 0.249 



0.008 

 0.197 



0.008 

 0.052 



North Dakota soil ( i ) | 



Unheated-soil extract 

 Heated-soil extract 



O.IOO 



1.080 



0.050 

 0.807 



0.050 

 0.273 



North Dakota soil (2) | 



Unheated-soil extract 

 Heated-soil extract 



O.IOI 



0.986 



0.037 

 0.758 



0.064 

 0.228 



Decrease of Soluble Matter in Heated-Soil 



Extract 



BY Treatment with 





Unheated-Soil. 











Total solid 

 matter. 

 Per cent. 



Organic 

 matter. 

 Per cent. 



Inorganic 

 matter. 

 Per cent. 



New York soil (2) | 



Before treatment 

 After treatment 



0.239 

 0.031 



0.179 

 0.019 



0.060 

 0.012 



North Dakota soil (3) | 



Before treatment 

 After treatment 



0.756 

 O.IOO 



0.576 

 0.052 



0.180 

 0.048 



In examining these results one is struck by the enormous in- 

 crease of soluble matter produced by heating. This increase 

 varies somewhat with different soils, depending upon the amount 

 of organic matter present, the length of time heated, and the 

 intensity of the heat, but in general the soluble matter in extracts 

 of heated-soils is from six to ten times that contained in the 

 extracts of the same soils before heating. The increase in the 

 organic matter is greater than that in the inorganic matter, but 

 still the latter is evidently increased several times. With such 

 large amounts of both organic and inorganic matter made avail- 

 able in soils by heating, one can understand the preference of 

 certain plants for places which have been burned over. It is 

 interesting to note that where the heated-soil extract was perco- 

 lated through and allowed to stand for a time with the unheated- 



