SUBCLASS EUBASIDIAE 469 



further division, even to the recognition of four or five orders. The author 

 conservatively recognizes two orders, Polyporales (Aphyllophorales) and 

 Agaricales. It must be confessed that the distinction between these two 

 groups is not sharp at some points, either from convergence in structure 

 of two otherwise very distinct orders or because one grades into the other, 

 representing a phylogenetic relationship. 



The great Swedish mycologist Elias Fries made extensive studies upon 

 the Hymenomycetes as well as upon other fungi for about sixty years. 

 His original classification was based upon the studies of Persoon with 

 whose later work his earlier publications were contemporaneous. Per- 

 soon's chief works were his Synopsis Methodica Fungorum, 1801, and 

 Mycologia Europaea, 1822-1828. The work of Fries, which is used as the 

 standard upon which the nomenclature of many groups of fungi (includ- 

 ing the Hymenomycetes) is based, is his Systema Mycologicum, in four 

 volumes, 1821-1832. His latest important work was Hymenomycetes 

 Europaei, 1874. The majority of the students of this group of fungi have 

 followed the Friesian system with minor modifications. He recognized five 

 families within the limits of the Hymenomycetes as follows : >i\ 



Agaricaceae: hymenium on radiating gills or lamellae. 



Polyporaceae : hymenium lining the surfaces of small pores or tubes. 



Hydnaceae: hymenium spread over spines or protuberances. 



Thelephoraceae : hymenium unilateral, spread over a firm, smooth or corru- 

 gated, under or upper surface. Mostly membranous, leathery, etc. 



Clavariaceae: hymenium spread over the surface of smooth, simple or branched 

 clubs. Mostly fleshy. 



Several families have been segregated from those above. In the au- 

 thor's first book in addition to the foregoing there were recognized the 

 Exobasidiaceae, segregated from the Thelephoraceae, and the Boletaceae 

 and Fistulinaceae, separated from the Polyporaceae. 



As mentioned in the preceding chapter the studies by Juel (1896, 1916) 

 and of Maire (1900, 1902) showed that in the Basidiomyceteae a distinc- 

 tion could be made as to the position of the spindle in the meiotic division 

 of the diploid nucleus of the basidium. This appeared to be correlated 

 more or less with the relationship of the groups. In some the basidium is 

 more slender and the diploid nucleus occupies an approximately central 

 position. The spindle of the first meiotic division is parallel to the longi- 

 tudinal axis of the basidium as are the two spindles of the subsequent 

 divisions of the two daughter nuclei. The nuclei then mostly migrate to 

 the upper part of the basidium where the sterigmata are formed. Such 

 basidia are stichobasidial. In other Basidiomyceteae the basidium is 

 broader above and the diploid nucleus is located in the somewhat widened 

 upper portion. The first nuclear spindle is more or less transverse and the 

 next two spindles also transverse, usually at right angles to the axis of 



