CARPOSPOREM. 



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Z31 



dependent spines like icicles, the surface of which bears the hymenium, &c. In many- 

 cases the fructification is naked ; in others the lower side of the pileus is covered with a 

 membrane which is afterwards ruptured [njelum partiale), or the pileus and stalk are both 

 enveloped in such a membrane {'velum uni'versale) ; or finally, in a few species {Amanita) 

 both are found. This formation of a velum is connected with the entire growth of 

 the whole fructification ; the naked pilei are essentially gymnocarpous, those covered by 

 a velum indicate a transition to the angiocarpous fructifications of the Gasteromycetes. 

 Jlgaricus 'variecolor is to a certain extent an intermediate form between those with naked 

 pileus and those furnished with a universal velum. The fructification in this species 

 .arises as a slender cone on the mycelium (Fig. 225, /, a, b), consisting of parallel 



Fig. 225. — Agaricus variecolor. /mycelium m, with yoimg 

 fructifications a b (natural size) ; c longitudinal section of one of 

 the latter (magnified) ; //an older fructification, with commence- 

 linent of the formation of the pileus ; ///the same in longitudinal 

 section ; IV s. more mature pileus, v the velum. The lines in the 

 Bctions indicate the course of the hyphae. 



. ■. .'li. 



Fig. 226. — Agaricus campeslris (natural size). 



fhyphae growing at the apex (/, c) ; an outer layer of hyphae is present at an early stage 

 'Surrounding the whole body as a loose envelope; afterwards the direction of growth 

 alters, the branches of the hyphae turn outwards beneath the apex (77, 777) and thus form 

 ^the pileus {IV), the margin of which continues to grow centrifugally ; the lamellae are 

 formed on its under-surface : as the distance of the margin of the pileus from the stalk 

 increases, the loose peripheral layer of hyphae becomes stretched {IV, 1;), and forms a 

 rudimentary universal velum. An example of the formation of a stalked pileus with a partial 

 velum is afforded by the common mushroom {Agaricus campestris). Fig. 226 shows at ^ a 

 small piece of the greatly extended reticulately anastomosing mycelium {m), from which 

 spring a number of fructifications ; these are at first solid pear-shaped bodies composed 

 of young hyphae all similar to one another. At an early stage the tissue of hyphae gives 

 way beneath the apex, leaving an annular air-cavity (77, /), the upper wall of which forms 



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