1915] 



OVERIIOLTS STUDIES IX THE POLYPORACEAE 669 



The genera treated by him contained 164 species in all, of 

 which probably two-thirds were in the single genus Polyporus. 

 This genus was divided into 3 sections, Favolus, Microporus, 

 and Polystictus, the first named being later raised to generic 

 rank. The section Microporus contained by far the largest 

 number of species. It was divided into 5 subgenera : Mesopus, 

 Pleuropus, Merisma, Apus, and Resupinatus. This arrange- 

 ment was continued in his 'Epicrisis Systema Mycologicum, ' 

 published in 1836-38. In the meanwhile the genera Trametes, 

 Cyclomyces, Ilexagona, Favolus, Laschia, and Porothelium 

 had been carved from the old genus Polyporus, and the num- 

 ber of species described had increased to 361 (entirely exclu- 

 sive of the genus Boletus). Of these, 280 were included in 

 the genus Polyporus. The same disposition of the pore fungi 

 was followed by Fries in his last publication, 'Hymenomy- 

 cetes Europaei,' in 1874, and, indeed, that system has either 

 been followed in its entirety since or has served as a founda- 

 tion for all other systems of classification that have been pro- 

 posed from time to time by others. 



Correlated with the increase in the number of described 

 species there is manifest a tendency on the part of some later 

 writers toward a change in the conception of what should 

 constitute a genus. There has been a tendency away from 

 the old idea of large genera containing a heterogeneous col- 

 lection of species, and toward the breaking up of genera into 

 smaller units consisting of closely related individuals. This 

 tendency finds its best expression in the work of Karsten, 

 Quelet, and Murrill, each of whom has published papers deal- 

 ing with the classification of the Polyporaceae. 



IMPORTANT MICROSCOPIC CHARACTERS USED BY EARLIER WORKERS 



Having glanced at the beginnings of the various classifica- 

 tions that have been proposed, we may now turn our atten- 

 tion to an analysis of the characters used in separating genera 

 and species. For the most part the generic characters were 

 macroscopic ones, such as presence or absence of a stipe, con- 

 sistency of the sporophore, nature of the hymenium, etc., — 

 characters that arrested the attention of the collector without 



