STRUCTURE. 19 
it pushes through the soil, it gradually loses its globose form, 
becomes more or less elongated, and in this condition a longitu- 
dinal section shows the position of the future gills in a pair of 
opposite crescent-shaped darker-coloured spots near the apex. 
The dermal membrane, or outer skin, seems to be continuous 
over the stem and the globose head. At present, there is no 
external evidence of an expanded pileus and gills; a longitu- 
dinal section at this stage shows that the gills are being deve- 
loped, that the pileus is assuming its cap-like form, that the 
membrane stretching from the stem to the edge of the young 
pileus is separating from the edge of the gills, and forming a 
veil, which, in course of time, will separate below and leave the 
gills exposed. When, therefore, the mushroom has arrived 
almost at maturity, the pileus 
expands, and in this act the 
veil is torn away from the 
margin of the cap, and re- 
mains for a time like a collar 
around the stem. Fragments 
of the veil often remain at- 
tached to the margin of the 
pileus, and the collar adhe- 
rent to the stem falls back, 
and thenceforth is known as 
the annulus or ring. We 
have in this stage the fully- 
developed hymenophore,— 
the stem with its ring, sup- 
porting an expanded cap or 
pileus, with gills on the under 
surface bearing the hyme- Fic, 2.—Section of Common Mushroom. 
nium.* J longitudinal section cut through the pileus and down 
* Ehrenberg compared the whole structure of an Agaric with that of a mould, 
the mycelium corresponding with the hyphasma, the stem and pileus with the 
flocci, and the hymenium with the fructifying branchlets. The comparison is no 
less ingenious than true, and gives a lively idea of the connection of the more 
noble with the more humble fungi.—LZhrb. de Mycetogenesi. 
