HYMENOMYCETES 363 



the pileus, when young, is globose, with its margin incurved 

 or pressed straight to the stem, and on expanding, the gills 

 are at once exposed, and remain so until they are com- 

 pletely developed and the spores are mature. An advance 

 on this arrangement is seen in those species provided 

 with a secondary veil, which originates from the upper 

 portion of the stem as a thin membrane, and is attached to 

 the margin of the pileus. This membrane grows and keeps 

 pace with the expanding pileus, thus concealing the gills 

 until the spores are nearly mature, when it breaks away 

 from the margin of the pileus and forms a collar or ring 

 round the stem, or in some instances almost entirely dis- 

 appears. In the highest type the entire sporophore is 

 enclosed in a universal veil which is buried in the ground. 

 After the pileus and gills are differentiated the universal veil 

 is ruptured, and the sporophore is elevated above ground 

 on a quickly growing stem, the universal veil remaining as 

 a basal sheath round the stem, and now called a volva, or 

 in many instances the upper portion of the universal veil 

 adheres to the pileus, where it is torn into patches as the 

 pileus increases in size. Some species furnished with 

 a universal veil have also a secondary veil, thus protecting 

 the hymenium until maturity; in other species the 

 secondary veil is absent. 



The primary divisions or sections of the Agaricineae are 

 founded on the colour of the spores, an arrangement which 

 is by no means artificial as it appears to be at first sight. 

 The colour of the spores when thrown down in a mass on 

 paper, and not as seen by transmitted light, is used for 

 discriminating the sections, which are as follows : Melano- 

 sporae, spores black. Porphyrosporae, spores purple-black. 

 Ochrosporae, spores ochraceous brown or rust-colour. 



