CARPOSPOREM. 
337 
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 {'velum par tiale), 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. 
Agaricus '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, 7, a, b), consisting of parallel 
W 
Fig. 225. — Agariais variecolor. /mycelium m, with young 
fructifications a b (natural size) ; c longitudinal section of one of 
the latter (magnified) ; // an older fructification, with commence- 
ment of the formation of the pileus; ///the same in longitudinal 
section ; IV ^ more mature pileus, v the velum. The lines in the 
sections indicate the course of the hyphas. 
Fig. 226.—AgariCHs camj^eslris (natural size). 
hyphae growing at the apex (/, c) ; an outer layer of hyphse 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 (//, ///) and thus form 
the pileus (ir), 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 {W^ t;), 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 'd 
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 (//, /), the upper wall of which forms 
z 
