154 A TEXT-BOOK OF BOTANY 
of the markets will serve as an illustration. The myce- 
lium of white branching threads spreads extensively through 
the substratum of decaying organic material, and by those 
who grow mush- 
rooms is called 
spawn. This my- 
celium, although 
the least conspicu- 
ous part of the 
mushroom, is, of 
course, the real 
vegetative body. 
Upon this under- 
ground mycelium 
little knob-like pro- 
tuberances arise 
(buttons), growing 
larger and larger 
(Fig. 145) until 
they develop into 
the umbrella - like 
structures common- 
ly spoken of as 
mushrooms (Fig. 
146). This um- 
brella-like — struc- 
ture, however, cor- 
responds to the 
Fie, 147.Sections through the gills of « common sporophores that 
mushroom: A, gills hanging from the pileus; B, & 
single gill showing the basidium layer; C, much arise from the my- 
enlarged view, showing the basidia-bearing spores. ¢eliqg of other groups 
-— After Sacus. 
S 
SSS 
ee 
oe =p; 
of Fungi, except 
that it includes a large number of sporophores organized 
into a single large body. Therefore, the real mushroom 
body is a subterranean mycelium, upon which the struc- 
