The Relation of Fungi to Other Plants 
lost their power of constructing such food, and also their green 
granules by which this work of construction may be carried on. 
The life history and structure of fungi 
has been studied so minutely that one is 
able to arrange them in three well- 
marked classes: 
The first class, the algal-like fungi 
(Phycomycetes), includes bread moulds 
and several of those fungi which cause 
diseases of plants and animals—the 
downy mildew on the grape, the potato 
rot, the common white mould which 
fastens dead flies to the walls or window PAROS, 
panes in the autumn, and the fungus Bread mould (mag- 
which grows on salmon piled) 
and causes them to die in great numbers. The 
plant of these fungi is cobwebby, sometimes 
growing within the cells of the plant substance on 
which it lives, and sometimes growing both 
within and on the surface. A freshly moulded 
piece of moist bread shows the bread covered with 
exquisitely fine transparent threads, which con- 
stitute the plant. Later, spore cases containing 
tiny black spores will be seen, which give a del- 
Spores borne in del- jcate gray tint to the plant at first, but later form 
icate membran- 4 black, repulsive mass as their numbers increase. 
fed) (magni- These plants are regarded as descendants of de- 
generate alge, which lost their power of inde- 
pendent existence through stealing their food 
instead of making it for themselves. 
The second class, the spore-sac fungi, 
produce their spores in delicate membranous 
sacs. The spore-sac fungi vary greatly in 
size, habit, and structure. Most of them 
are inconspicuous members ‘of the plant 
world, as the yeast plant, by which our 
bread is raised ; the fungus which causes 
the peach leaves to curl and the black knots Spores borne on little 
spicules (magnified) 
to appear on cherry and plum trees. 
The third class is made up of all fungi which bear their 
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