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Dr. Arthur Hollick exhibited and commented upon two speci- 
mens recently brought to light in overhauling unnamed material 
in the paleobotanical collections, as follows: 
A fossil fungus allied to Polyporus, from the Carboniferous of 
West Virginia, described and figured in Afycologia for March, 
1910, under the name Pseudopolyporus carbonicus gen. et sp. 
nov., and a fossil alga, unusually well preserved and defined, 
from the Devonian of Delaware County, N. Y., which will be 
described as a new species under the genus Thamnocladus. 
Mr. E. D. Clark delivered a paper on “‘The Changes Produced 
by the Heating of Soils and their Effects on the Growth of 
Pyronema and other Fungi.’’ The following synopsis was pre- 
pared by Mr. Clark. 
At a former conference we outlined the proposed investigation 
upon this subject and at this time we shall discuss the results 
we were able to obtain. Pyronema grows in nature only upon 
soil that has been burned over, but as far as we know, no one 
until Kosaroff, and he only recently, has attempted to explain 
this fact. He proved that this fungus can be readily cultivated 
upon heated soil in the laboratory, but not upon soil which has 
not been so treated. Furthermore, he claimed to have been 
able to render unheated soils favorable to Pyronema by washing 
the soil with water and in other ways. All of this led him to 
believe that in unheated soils there are substances present, toxic 
to Pyronema, which are destroyed by the heating. This expla- 
nation based upon the presence of toxic substances is in accord 
with some of the more recent theories which find in such toxic 
organic matter the cause of the lack of fertility shown by certain 
soils. 
We tried to extract a soluble substance from unheated soils 
which would show toxic effects upon Pyronema, and tested these 
extracts under many different conditions, but we failed in every 
case. This led us to believe that possibly the cause of the luxuri- 
ant growth of this fungus on burned soils was not due to the 
destruction of toxic materials in the unheated soil, but rather to 
the setting free of certain food materials not available to the 
plant before the soils were heated. Pots of soil were heated to 
