BOTANY. 85 
or fruit, and the proportion of the size of the fruit to the 
mycelium or threads, have served as the basis of a classifi- 
cation of the Fungi. The mushroom, the puff-ball, the 
smut, the mildew, the truffle, and mould, are familiar ex- 
amples of the different poem of Fungi. This classification, 
like all similar attempts, suffices, so long as types so diff 
ent as a mushroom and ne are compared. W TM are 
commonly collected as mushrooms are only the fruit of the 
fungus Agaricus: the greater part of the mildew examined 
show only the myc 
pů 
elium or threads of the f fungus Botrytis. 
The mushrooms belong to the order Hymenomycetes, so 
called from the hymenium, or part supporting the fruit, 
being so prominent, the threads being inconspicuous. The 
mildew (Fig. 105) illustrates the ] 
derive their name from the Hyphi, or th 
developed, the fruit dropping off. 
The difficulty of classification arises from the fact that 
from time to time individuals are discovered whic 
yphomycetes, which 
reads, being so much 
h do not 
present such striking contrasts as the mushroom and mildew, 
their characters being so little defined as to make it im- 
possible to say to what groups they belong. All such 
intermediate forms, the source of so much ouis in the 
arrangement of an herbarium, are most important proofs 
of the truth of the theory of the gradual transformation 
of plants. Not only is it true that in the Fungi the orders 
pass insensibly into each other, but there are also forms of 
which it is doubtful whether they are Fungi, some botanists 
still regarding them rather as Algae. Thus, the Peronospora 
(Fig. 106), differing from Botrytis (mildew) in its continuous 
cells, the partitions of Botrytis (Fig. 105) being absent, is 
according to Prof. Haeckel, a transitional form which links 
the Algae through Vaucheria (Fig. 107) with the Fungi, 
though the Peronospora is usually regarded as a Fungus, 
it having no chlorophyll. The Achlya, sometimes called 
: prelecnia: formerly considered an Alga, seems to be only 
