TAXONOMY 275 



"bricks" are put in the horse manure bed only after the heat has 

 first disappeared. The beds are then watered well and in a short 

 time the sporophores or fruiting bodies of the fungus spring up. 

 The mycelium or vegetative body of Agaricus which develops 

 in the soil from spores (basidiospores) is white and thready. On this 

 mycelium develops little buttons, first about the size of a pin head, 

 becoming later pea size and then assuming a pear-shaped form. At 

 this stage the sporophore consists of a cylindrical solid stipe or stalk 

 and a pileus or cap. The border of the pileus is joined to the stipe 



FIG. 144. Meadow mushroom (Agaricus campestris L.). A, view showing 

 under side of pileus; g, gills; a, annulus, or remains of the veil attached to^the 

 stipe; B, side view; s, stipe; a, annulus; p, margin of pileus, showing at intervals 

 the remains.of the veil. (Gager, after W. A. Murrill.) 



by means of a "partial veil." Within this veil is found a circular 

 cavity, into which the gills grow. At first the stipe grows faster than 

 the rest of the fruiting body. The pileus expands transversely and 

 the gills keep pace. After a while the veil ruptures, leaving a portion 

 attached to the stipe. This constitutes the annulus or ring (true 

 annulus). The hyphae in the pileus form the Tela contexta. If we 

 make a section through a gill, the hyphae are seen to run longitudi- 

 nally. The central part is called the trama] next and outside trama 

 is the sub-hymenium; next, hymenium, consisting of basidia (hence a 



