FUNGI. 321 
number of individual fungi that grow vertically 
together instead of horizontally in a crust or tuft, 
and thus endowed with greater powers of endur- 
ance and longevity. In the mushroom it might 
be possible to separate a filament from the spawn, 
and trace its course up the stem, through the cap, 
down one of the gills to the surface, where it bears 
sacs or basidia with their four naked spores, And 
this isolated fruit-bearing thread of the mushroom 
would be equivalent to an individual mould-plant, 
with its free filaments bearing terminal or lateral 
spores. It is therefore in strict accordance with 
morphological rules to consider the whole mush- 
room as typically an aggregation of separate in- 
dividual fungi of lower type, consolidated together 
into one individual. And as if to favour this 
view, we find that, under certain circumstances, 
the common green mould, Penicellium crustaceum 
(Fig. 37), instead of forming, as it usually does, a 
continuous stratum of separate individuals, breaks 
up into little tufts, the threads composing which 
are so incorporated as to form a sort of common 
stem with a globose head of spores, thus making 
an approximation to the stem and cap of the 
mushroom. It is thus exceedingly interesting to 
find the same laws of morphology that control the 
highly organized forms and structures of the trees 
of the forest, applicable to the humblest mould 
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