Seaver-Clark : Studies in Pyrophilous Fungi 123 



In order to prove the identity of the species, in the spring 

 of 1908 a pile of dead grass and leaves was raked together 

 on the ground and burned, giving rise to a burnt place similar 

 to those on which Pyronema omphalodes (Bull.) Fuckel was 

 known to occur. As soon as the first rain occurred after the 

 burning of this material a few of the plants from the labora- 

 tory were placed in the ashes and on the ground where the fire 

 had been. In about ten days a good growth of Pyronema ompha- 

 lodes (Bull.) Fuckel was found, the plants occurring in confluent 

 masses as usual. These plants were taken into the laboratory and 

 inoculations made from them on heated-soil. These at once pro- 

 duced mycelium radiating out from the point of infection and 

 later produced an abundance of fruit, the ascocarps being scat- 

 tered as is usually the case in laboratory grown material. 



Some of the laboratory plants show rather well developed, 

 hyaline, septate hairs, although these are not a conspicuous char- 

 acter. The color also varies much from bright rose or salmon 

 to almost white. The paler plants are usually those produced 

 on less favorable substrata. The fungus has doubtless been 

 described under several names. 



Summary 



1. Contrary to the statement of Kasaroff, our experiments have 

 failed to show the presence of a soluble, toxic substance in 

 unheated-soil which will retard the growth of Pyronema when 

 applied to heated-soil. 



2. Heating the soil to a high temperature brings about chemical 

 changes indicated by the following: (a) The extract of heated- 

 soil is of a bright amber or reddish-brown color and possesses 

 a characteristic odor while the extract of unheated-soil is color- 

 less and almost odorless, {h) the amount of soluble material in 

 the extract of heated-soil is increased to approximately* six to 

 ten times that of the extract of the same soil unheated. 



3. The materials rendered available by the heating of the soil 

 serve as food for Pyronema, as is indicated by the following: (a) 

 The conditions necessary for the production of a highly colored 

 extract in soil are the conditions most favorable to the growth 



* The exact increase will vary with the soil and manner in which it is 

 treated, temperature, length of time heated, etc. 



