CONFERENCE NOTES. 
The regular monthly conference of the scientific staff .and 
students of the Garden met in the library on Wednesday, Decem- _ 
ber 1, and was presided over by Dr. W. A. Murrill. Mr. E. D. 
Clarke, the first speaker of the afternoon gave a paper on the - 
subject of “The Relation of Organic Matter to Soil Fertility.” 
The following synopsis was prepared by Mr. Clark : 
From Liebig’s time nearly to the present, the necessity for crop 
rotation was explained by the great chemist’s theory of the 
mineral requirements of the soil. According to this theory it is 
the depletion of these ea substances or the change of their 
relationship by the growing plant that lowers the fertility of the 
soil for that plant, making necessary the change of crop or 
the addition of eratie fertilizer to stop or repair the loss 
caused by that sort of owever, recent work, especially 
that of Schreiner and Cee seems to show that the 
mineral constituents of soils are by no means the sole factor in 
questions of fertility. This work indicates that plants, during 
life or by decomposition after death, give to the soil certain or- 
ganic substances which may make that soil more or less toxic to 
the plant which gave rise tothem. In fact, definite crystalline 
organic compounds have been isolated from soils known to be 
poor for certain crops. Schreiner considers it likely that the 
oxidizing powers of the plant roots and free access of atmos- 
pheric oxygen through tillage, normally result in the oxidation 
of such harmful substances to others less injurious to the crop. 
Bolley has reported an experiment upon the effect of steaming 
a worn-out wheat soil which showed that such treatment rendered 
this soil capable of producing a good yield of wheat in the two 
following years. 
It was with these ideas in mind that we became interested in 
the fungus Pyronema omphalodes which occurs only on recently 
burned places as noted by Seaver and also Kosaroff. Both re- 
port that it can be cultivated very easily in the laboratory upon 
soil that has been heated to the temperature of boiling water or 
above, while they were unable to grow it upon an unheated soil. 
