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matted together they form a kind of web or false tissue ; they never 
coalesce by fusion of their walls so as to form a continuous tissue. 
They present a similar appearance to mushroom-spawn, and. collectively 
form the mycelium, or vegetative system of the fungus, and extract 
their nourishment from the plant selected as their host. The mycelium 
penetrates the woody portion of the root and produces effects of a 
similar character to those developed by dry-rot (Merulius laerymans), 
so that ultimately the stoutest roots may be crumbled to pieces 
between the finger and the thumb; the bark of the collar decays, the 
decay extends to the trunk, and the tree can be pulled out of the 
ground with little more difficulty than a common stake. 
The erratic manner in which the attacks of the fungus are made 
may possibly be due to slight variations in the compactness of the 
surface soil. In all probability the mycelium is able to penetrate soils 
of a certain texture more easily than others. 
In one garden all the plants, chiefly strawberries, within a large 
irregular patch were first attacked; the mycelium had then attacked 
the box-edging and worked below the surface of the walk to the 
opposite side, where it attacked a number of fruit-trees in full bearing. 
In some seasons the reproductive system of the fungus is not 
developed ; its vegetative system may permeate spaces many square 
yards in extent without a single perfect specimen making its appearance. 
In other seasons the reproductive state is developed in great abundance 
in certain localities, although in adjacent localities, in which the 
subterranean state is equally plentiful, there may not be a single 
reproductive specimen. 
The reproductive system is terrestial, and makes its appearance 
above the surface in the form of small spherical bodies, which break 
through the soil singly or in clusters of from five to ten. At first 
they are whitish, fleshy, and apparently homogeneous, but inless than 
48 hours they assume the form of small puff-balls; the fleshy portion 
is converted into countless millions of dark-brown spores, resembling 
extremely fine snuff, and contained in a thin membranous spherical 
envelope. At length the sphere exhibits a minute aperture at the 
apex, and the spores escape in myriads, so that, in addition to the 
indefinite underground extension by means of its vegetative system, 
the germs of new individuals are distributed broadcast over extensive 
districts by the lightest breath of air. 
It is rarely found to attack trees growing in damp situations. 
Although I was assured that instances of the kind were known, none 
came under my observation. In the valuable orchard of Mr. Horn, 
near Cambridge, not a single tree was attacked on the low ground, but 
on a dry sloping bank many trees had been killed and others were 
dying at the date of my visit. 
Trees planted on fern-land are especially liable to be attacked by 
this fungus. In most cases it will be found that fragments of the 
underground stems of fern have been left in the soil, and when 
