Bi'itish Fmwi. 



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tlie modified tips of ordinary liyph^e. Spores produced 

 on basidia are called hasidiospores, Basidia are 

 usually produced in considerable numbers, and stand 

 side by side, their tips collectively forming the free 

 surface of the structure, which is known as the 

 Tiymenium. In addition to basidia, other structures 

 are usually present in the h\menium, csiiled paraphyses 

 and cystidia. The former resemble basidia in shape, 

 but "are usually smaller, never produce sterigmata, 

 and are by some authors considered as barren basidia. 

 Cystidia are cylindrical or fusiform cells, usually 

 much larger than the basidia in the same hymenium, 

 and project above the general surface. In some sec- 

 tions of the Basidiomycetes they are very numerous, 

 giving to the hymenium a velvety appearance ; in 

 others entirely absent. The most important function 

 of cystidia is in connection with transpiration, or the 

 escape of water from the tissues. This function can be 

 well studied in the species of Peniopliora which form 

 broadly-extended whitish or buff-coloured patches on 

 old trunks, to which they are firmly attached by the 

 w^hole of the under surface, the upper or free surface 

 being entirely covered with the hymenium. Under a 

 pocket-lens the hymenium appears minutely setulose 

 or velvety, and if a thin section through the fungus 

 is examined under the microscope, the under surface 

 will be seen to consist of densely interwoven hyphaB, 

 from which originate the elements of the hymenium, 

 basidia, paraphyses, and numerous, relatively very 

 large, fusiform cystidia. These latter are colourless, 

 and have their walls at first perfectly smooth, but 

 with age the portion projecting above the level of 



