BASIDIOMYCETES. 323 



also upon all parts of the young stems and leaves. He even sprinkled 

 the young plants with germinated spores, and in one series of experi- 

 ments brought the young rootlets in contact with the promycelium 

 and sporidia of the germinating spores. In no case, however, was 

 there any penetration of the fungus into the host plant. 



(g) The most important genus of the order is Ustilago, which con- 

 tains many species, the most common of which are U. carbo, the 

 gmut of wheat, oats, barley, and many other grasses ; U. Maydis, the 

 smut of Indian corn ; U. de*truens, on Setaria glauca; U. utriculosa, 

 on species of Polygonum ; IT. itrceolorum, on many species of Carex. 

 Tilletia contains several species, but one of which T. caries has yet 

 been detected in this country. Of Urocystis we have several species, of 

 which U. cepulce, on onions, and U. pompholygodes, on Ranunculacese, 

 are best known. 



IV. CLASS BASIDIOMYCETES. 



416. The plants of this class are among the largest and 

 finest of the fungi. They are mostly saprophytes, provided 

 with an abundant mycelium, which ramifies through the 

 nourishing substratum, and from which there arises after- 

 ward a spore-bearing growth, the sporocarp. The spores, of 

 which but one kind is yet certainly known,* are produced 

 upon slender outgrowths from the ends of enlarged cells, 

 termed basidia. The basidia are usually so arranged as to 

 form an hymenium, which is at length external in Hymeno- 

 mycetes, and internal in most Gasteromycetes. 



417. The sexual organs probably precede the formation 

 of the sporocarp, but they have been but little studied. 

 (Ersted discovered! bodies in Agaricus variabilis which, 

 judging from his description, bear a considerable resemblance 

 to the sexual organs of Peziza. Whether they occur through- 

 out the class is at present entirely unknown, and as (Er- 

 sted's discovery has not been confirmed by other observers, 

 the whole question as to the sexual organs of the Basidiomy- 



* (Ersted, in " Kongeliire Danske Videnskabernes Selskabs Forhand- 

 linger," Copenhagen, 1865 (translated in Qr. Jour. Mic. Science, 1868, p. 

 18), describes certain little stalked bodies which he found growing upon 

 the mycelium of Agaricus variabilis, and which he regards as conidial 

 in their nature. Spermatia also occur on the Tremellini. 



f Described in bis paper just referred to above. 



