1914J Guy West Wilson 209 



likely that the truth of the matter lies somewhere on the borderlines 

 of the three sciences indicated." Beyond this we are not at present 

 prepared to go, save to remark that the widely divergent soils 

 studied severally by these observers probably contained substances 

 which justify the conclusions of each. If each of these investi- 

 gators had studied all the soils referred to in these papers, the inter- 

 pretation of the results obtained might have been more harmonious. 



Summary of general conclusions. All the plants used in this 

 work showed a slight acceleration of growth and vigor on soil which 

 had been heated to a temperature of 95 ° C. In the case of buck- 

 wheat, acceleration was quite marked. 



All the plants used in these experiments showed a retardation 

 of growth on soils subjected to a heat of 135 or 175 C, the re- 

 tardation being especially marked for plants grown on soil heated 

 to the higher temperature. 



Plants grown on heated soil were more susceptible to attack by 

 parasitic fungi than those grown on unheated soil, although the sus- 

 ceptibility to such attacks did not increase proportionately as the 

 growth of the host decreased. 



Soil fungi grew more abundantly on the soils which had been 

 subjected to high temperatures, in one instance seriously interfering 

 with the experiment. 



The effect of heating soils upon the crop grown varies with 

 the temperature to which the soil is subjected, the kind of soil used, 

 and the nature of the crop grown upon it. 



In conclusion most hearty thanks are due to Professor William 

 J. Gies, to Dr. Fred J. Seaver and to Dr. Ernest D. Clark for their 

 suggestions and advice during the progress of the work. 



