Seaver-Clark : Studies in Pyrophilous Fungi 121 



and the heavy precipitates obtained with lead acetate, silver 

 nitrate, and calcium hydroxide, might well be due to the presence 

 of organic acids. The positive Molisch test indicates carbohy- 

 drates or their decomposition products, while the strong reducing 

 action on Fehling solution would seem to confirm the assumption 

 that carbohydrate substances are present. It is not at all im- 

 possible that the partially disintegrated cellulose of the bodies 

 of plants previously growing on the soil, would be broken up into 

 still smaller fragments of the original enormous molecule, and 

 that these smaller fragments would still retain some of their car- 

 bohydrate characteristics together with the added one of acidity. 



We next examined the ash of the North Dakota heated-soil 

 extract in a qualitative manner to discover if possible the nature 

 of the inorganic substances in the extract. The ash of the North 

 Dakota soil was used for the reason that this was obtained in 

 considerable quantity and that the extract of this soil was un- 

 usually favorable as a culture medium for fungi, probably owing 

 to the large amount of organic matter originally present in the soil. 

 The ash of the unhealed North Dakota soil was pure white and 

 soluble in water (lOO c.c). Upon analysis the ash was found to 

 consist principally of the sulphates of sodium, potassium, mag- 

 nesium and calcium ; we were however able to find scarcely a 

 trace of phosphates. About one-half of the ash of the extract of 

 heated North Dakota soil was found to be soluble in water. In 

 the soluble portion of the ash, sulphates of potassium, sodium, 

 magnesium and calcium, etc., were found. In the insoluble part 

 of the ash, we found principally calcium sulphate with some 

 manganese, iron and traces of phosphates, etc. Calcium is thus 

 seen to be present in considerable quantities in the extracts of 

 lieated- and unheated-soils and it may be, from the well-known 

 stimulating and protective properties of calcium toward plants, 

 that this element along with the organic matter helps to give 

 heated soils some of their striking properties. 



Just as this work was being brought to a close we received, 

 upon request, a copy of an article (in galley proof) by Pro- 

 fessor T. L. Lyon, who is publishing the results of his investiga- 

 tions on the efifects of steam sterilization upon soils. With steam 

 heat he found the same great increase of soluble matter over 



