THE GILL 
i3 
bearing surface, also admirable protection for the maturing 
spores against adverse climatic conditions. Moreover, the 
entire sporophore is often very hard and woody. (It must, 
however, be remembered that some species are soft and 
adnate, with shallow pores or reticulations instead of true 
tubes.) 
The family Agaricaceae comprises those species in which 
the hymenial surface consists of radiating plates or gills, 
developed for the most part beneath a protective cap. 
Some species are more or less resupinate, and in one 
remarkable genus, Montagnites (not represented in Britain), 
the pileus is entirely absent. It fre¬ 
quents the arid deserts of Egypt. The 
entire plant is at first enclosed in a 
volva buried in the sand. Within the 
volva complete development takes 
place. At maturity the protecting 
membrane is broken, and the sporo¬ 
phore quickly raised on a tall stem. 
The spores are liberated from gills 
which occupy exactly the same posi¬ 
tion relative to the stem as those of 
any typical agaric, but are always 
without a pileus to protect them. 
A gill in transverse section consists of three layers. The 
central one, or trama, is composed of hyphae continuous with 
those of the pileus, and is bounded on each side by the sub- 
hymenial layer, on which the hymenium is developed. A 
gill is in reality a double membrane, folding like a fan 
around the trama. In the genus Schizophyllum the margin 
of the gill splits along the line of the trama for a short 
distance, the split part curling outwards (see Plate XLV.). 
The surface of the gill membrane in a typical agaric is 
closely packed with three kinds of club-shaped cells— basidia , 
pamphyses , and cystidici. 
From the gill surface of an 
agaric (highly magnified). 
A, basidia with spores; 
B, paraphyses or atrophied 
basidia; C, cystidia, or 
hypertrophied basidia. 
