STUDIES IN PYROPHILOUS FUNGI — II* 



CHANGES BROUGHT ABOUT BY THE HEATING OF 

 SOILS AND THEIR RELATION TO THE GROWTH 

 OF PYRONEMA AND OTHER FUNGI 



Fred J. Seaver and Ernest D. Clark 

 (With Plates 24-26, Containing 6 Figures) 

 (From the Laboratories of the New York Botanical Garden) 



Page 



I. Introduction 109 



11. Toxin theory lio 



III. Pyronema growth a food problem 112 



IV. Biological experiments with soil extracts 1 14 



V. Heated-soil and its extracts as nutrient media for fungi 116 



VI. Distillates from heated-soil extracts 117 



VII. Chemical studies of soil extracts 118 



a. Quantitative studies Ii8 



h. Qualitative studies 120 



VIII. Products of dry distillation of soil 122 



IX. Identity of the fungus 122 



X. Summary . 123 



I. Introduction 



Our observations noted in previous papers as to the occurrence 

 of Pyronema on burned-over or heated soil had been previously 

 noted by Kasaroff, who in this connection states that this striking 

 phenomenon could not be explained on the assumption that the 

 fungus had survived the heating, a subsequent infection being a 

 much more likely explanation. The results of numerous experi- 

 ments are not wholly consistent but point to certain conclusions. 



Kasaroff thought that the absence of growth on unheated-soil is 

 not due to the fact that through the process of heating more 

 material necessary to the fungus is set free but rather that the 

 unheated-soil contains constituents which render the growth of 

 the fungus impossible, which constituents are destroyed by heat- 



* Studies in pyrophilous fungi — I. Occurrence and cultivation of Pyronema, 

 was published in Mycologia i : 131-139. 1909. 



109 



