General Features 25 



In fact, nature usually supplies the spores provided we comply 

 with the other requirements, but to make certain we usually 

 supply them. Control experiments show that Pyronema cannot 

 be grown on unheated soil, even though the same soil is used 

 and all the other requirements are met (Fig. 13). It must be 

 borne in mind, however, that the spores in this case do not require 

 heating. In fact it is doubtful if they could withstand the 

 process. It is only the soil that should be heated. 



Later experiments conducted by the writer in cooperation 

 with Dr. E. D. Clark (Mycologia 2: 109-124. 1910), formerly 

 of the Department of Biological Chemistry of Columbia Univer- 

 sity, proved that the question of growth of Pyronema on heated soil 

 was purely a food problem. The heating renders insoluble 

 organic matter soluble, which material serves as an excellent 

 medium for the growth of many fungi as well as Pyronema. 

 The growth of Pyronema on steamed soil had been noted in 

 Europe but, so far as we are aware, no one who knew the fungus 

 had ever observed it in America. As full data on this subject 

 have been published in preliminary papers it seems unnecessary 

 to repeat them here. 



Whether other species of pyrophilous cup-fungi grow on 

 burnt soil foi the same reason has not been demonstrated but 

 it is suspected that this factor may influence them to a greater or 

 lesser degree. Betts (I.e.) mentioned the fact that he could 

 not produce sex organs in Ascobolus carbonarius on agar but that 

 they developed readily when germinated spores were transferred 

 to sterilized soil, indicating that the sterilized soil offered the 

 better medium. Pyronema, however, fruits readily on agar. 



15. Coprophilous Cup-fungi 



This term is applied to those species which grow exclusively 

 on the dung of animals, and some show a decided preference 

 for the dung of certain kinds of animals. Ascodesmis porcina 

 has been grown only on pig dung, first on material from Porto 

 Rico and later on the same kind of dung from New Jersey. It is 

 probable that such a species would grow on the dung of closely 

 related animals but up to date it has been found only on the 

 dung of the one kind. Others are not so discriminating in their 

 tastes but thrive on almost any kind of excrement. That 

 coprophilous forms can grow on other substrata is evident from 

 the fact that they are produced in cultures on agar. 



