254 THE VEGETABLE WORLD. 
result of the germination of these spores is that mycelium of which 
we have already spoken as being the reproductive apparatus of — 
the fungi, which are seen in the form of filaments at the foot of 
the mushroom in Fig. 319, 1. Fragments of this mycelium can 
multiply the plant much as a fragment of rhizome of a phanero- 
gamous vegetable does. It is on this principle that gardeners 
sow the mycelium, which they term mushroom spawn, and which 
may be preserved for many years without losing its germinating 
properties. In cultivating mushrooms a hotbed is prepared, con- 
sisting of horse-dung, covered with a bed of earth of about three 
feet thick, in which the mycelium is planted, watering it from 
time to time in order to maintain a certain degree of humidity. 
In a short time small tubercles will appear, which at a later 
period become young mushrooms. 
The Trurrix, belonging to the sub-order of Gasteromycetes, 
asserts its fungale characteristics by its membraneous sporang™ 
which are scattered on a serpentine vein-like hymenium, and 
enclosed in a concrete uterus. The sporidie are at first pulpy : 
There are two genera: Tuder, the common truffle, and Rhazo- 
pogan, the white truffle, the species being very generally dt 
over the temperate parts of the globe, growing ten or twelve inches 
beneath the surface of the soil. The R/izopogans have a sessile 
uterus, bursting irregularly, and marbled internally with anasto- 
mosing veins and sessile sporangia; the Tubers a closed uterus, 
marbled internally with veins. The sporangia are pedicillate and 
confined to the veins. 
The Common Truffle (7. cibarium) is of irregular form, nearly 
black in colour, and warty in appearance. It seems to affect the 
soil covered with woods, especially oak and beech woods, but there 
is no reason to suppose that there is anything approaching a parem 
bond between the truffle and the roots of trees among which it grows 
by preference. It develops itself as others of the mushroom ttt ; 
do, by spores, which make their appearance in the matured plan th 
They are singularly small, something less than the three-hundred 
part of an inch in diameter. When the trufile is left after ml 
to decompose in the sun, these spores produce whitish mage: 
analogous to the mycelium of the Agaracese. This mycelium, W 
buried in the soil, in due time reproduces the trufile. 
