F UNO I. HFMENOMFCE TES. 



133 



fructifications of the Gasteromycetes ; this is especially the case with Amanita. 

 Agaricus variecolor (Fig. 88) is to a certain extent an intermediate form between 

 those with a naked pileus and those with the velum universale. The fructification first 

 appears on the mycelium as a slender conical body (a and b] formed of parallel hyphae 

 with apical growth (c) ; at an early period an outer hyphal layer is distinguishable, forming 

 a. loose envelope round the whole body ; after a while the growth at the apex ceases ; 

 the hyphae bend outwards beneath the summit (77, 777) and thus form the pileus (7F), 

 the margin of which grows centrifugally; the lamellae make their appearance on its 

 under surface, and as the margin of the pileus advances further from the stipe, the loose 

 peripheral layer becomes stretched into a velum universale. The common mushroom, 

 Agaricus campestris, affords an example of the formation of a stalked pileus with a 

 velum partiale. Fig. 89 A gives a small portion of the widely spreading and reticulately 

 anastomosing mycelium (;), on which a number of fructifications are being formed ; 



KiG. 87. Gonidia-producing fructification of Boletus 

 Jlavidus in longitudinal section, slightly magnified ; 

 st stipe, hu pileus, hy hymenium, h the cavity beneath 

 the hymenium, v the velum partiale, he the separable 

 superficial layer of the pileus, f the continuation of the 

 hymenial layer on the stipe. 



FIG. 88. Agaricus variecolor. I mycelium m with' young gonidio 

 phores a and b (nat. size) ; c longitudinal section of one of them 

 magnified. // an older fructification with commencement of the 

 formation of the pileus. ///the same in longitudinal section. IV 'a 

 pileus in a more advanced state ; v the velum. The lines in the 

 longitudinal sections show the course of the hyphae. 



these are at first pear-shaped solid bodies (/) composed of young uniform hyphae, 

 and each of these bodies is a rudimentary stipe, from the upper part of which 

 the pileus will be developed. At an early period the hyphal tissue gives way in such a 

 manner as to form an annular air-cavity beneath the summit of the stalk (77, /) ; this 

 cavity enlarges with the growth of the whole body, its upper wall forming the under 

 side of the pileus, from which the radial hymenial lamellae grow in a downward 

 direction and fill up the cavity (777, /). The hyphae run from the base of the stipe to 

 the margin of the pileus and form the outer wall of the cavity; the central portion of the 

 stipe (IV, st} elongates, while the distance between it and the margin of the pileus con- 

 tinually increases. By this growth the hyphae beneath the cavity which contains the 

 lamellae become stretched and separate from the stipe from below upwards, and now 

 form a membranous veil ( V, v] running beneath the lamellae from the upper part of the 

 stipe to the margin of the pileus, into which the hyphae are continued. When at length 



