BASIDIOMYCETES 409 



transpiration in dry weather; they are withdrawn from direct insola- 

 tion, a fact which may be important in the lower forms with hyaline 

 spores whose power of germination may be influenced by direct sunlight. 

 Thus the spores of Schizophyllum commune and of Daedalea unicolor 

 germinate more slowly when they have been placed in the sunlight a few 

 hours than when kept in the dark. Finally, spore discharge may be 

 influenced in different ways, since in the Basidiomycetes the spores 

 are not shot out over a large area, as in the Ascomycetes, but are dissemi- 

 nated passively (by wind in the epigaeous forms). 



From these bracket fructifications, there is an uninterrupted transition 

 to stipitate forms; first, to those whose stipes are inserted laterally (Fig. 

 348), later (apparently for the better division of the static moments), 

 to the centrally stipitate pilei. Which irritability complex and what 

 correlated response conditions the hereditary form of the manifold 

 fructifications is still unknown. In any case, it is certain that as the 

 humidity and light relationships were determining factors for the forma- 

 tion of the fructifications, so also these factors materially influence 

 their form; thus, in the dark, Polyporus squamosus does not form a pileus 

 but its fructifications are branched like antlers and sterile. In cultures 

 of Lenzites saepiaria (Zeller, 1916) the early fructifications are clavarioid 

 although fertile, while the later ones more closely resemble the normal 

 daedaloid or lamellate forms found in nature. 



Along with this transition from resupinate crusts to centrally stipitate 

 pilei, there is a remarkable increase in mass, i.e., in weight and food 

 content of the fructification. Its dry weight amounts to approximately 

 10 per cent, and contains 30 to 50 per cent nitrogenous material, mostly 

 proteins of unknown composition, 20 to 40 per cent carbohydrates, 

 chiefly mannite and glycogen, and 2 to 6 per cent fat. Because of this 

 wealth of nutrients, those fleshy fructifications which are used for human 

 food are most ephemeral and will not withstand even transitory desicca- 

 tion; while those which are poor in digestible nutrients, the woody fructifi- 

 cations, are often adapted to extreme xerophytism; they can resume 

 their life processes after desiccation for a year and, consequently, may 

 attain an age of eighty or even more. 



Morphologically, as a consequence of the limitation of lateral 

 growth, there follows, with the transition from the resupinate crust to 

 the hypogaeous tuberous form, and to the epigaeous, centrally stipitate 

 fructifications, a general change in principle of growth. The resupinate 

 crusts and the brackets arise from a more or less expanded unlimited 

 hyphal tissue and consequently may become a meter in breadth, if there 

 is no limiting factor of growth. The fructifications of the higher forms, 

 however, arising from a spatially limited mycelium and tuberiform 

 tangles of hyphae, are somewhat influenced in size by the dimensions of 

 these tuberiform fundaments. With the lower forms, this limitation 



