STRUCTURE. 



ID 



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 stern 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- Fl - 2. Section of Common Mushroom, 

 nium.* A longitudinal section cut through the pileus and down 



* Elireiiberg compared the whole structure of an Agaric with that of a mould, 

 the mycelium corresponding with the hyphasraa, the stem and pileus with the 

 flocci, and the hymeniurn with the fructifying bran.chlets. The comparison is no 

 less ingenious than true, and gives a lively idea of the connection of the more 

 noble with the more humble f ungi. E/irb. de Myce!oyenesi. 



