118 RELATIONS OF SAPROPHYTES TO THEIR NUTRIENT SUBSTRATUM. 
twenty-four hours, is certainly many times as great as that of the entire mycelium 
which produced it; and it is quite incomprehensible how this mycelium, which for 
weeks only achieves a moderate development, and adds but little to its dimensions, 
is in a position suddenly, and in so short a time, to supply the amount of water and 
organic compounds requisite for the building up of the fructification. Epipogvum 
aphyllum exhibits a similar property. After producing nothing for two years 
excepting a few branches on its subterranean stem, it develops all at once and in 
a very short space of time fleshy stems with large flowers, and one asks with 
astonishment how the relatively small coral-shaped stock sets about obtaining the 
quantity of nutrient materials necessary for the construction of these flowering 
stems. We are here confronted again with the great mystery of periodicity, the 
solution of which we must for the present forego. 
Saprophytes are much more fastidious as regards the quality of their nutriment 
than one might expect. It is true that certain fungi are produced wherever there 
are plants in a state of decomposition, and to them it is quite indifferent whether 
the mouldered dust, which serves as a nutrient soil for their mycelia, has arisen 
from one species or another. Also in the case of orchids imbedded in vegetable 
mould, and in that of most of the mosses and liverworts adherent to the barks of 
trees, it is, as a rule, of no consequence whether the tree constituting the substratum 
is a conifer or a dicotyledon. But a large number of species are associated with the 
decaying remains of particular plants or animals only. For example, certain small 
species of Marasmius, belonging to the group of the Agarici, occur only on moulder- 
ing pine-needles; another small fungus, Antennatula pinophila, is found exclusively 
on fallen needles of the Silver Fir; Hypoderma Lauri, which resembles small black 
type on rotting laurel leaves, and the tiny Septoria Menyanthis on leaves of the 
Bog-bean (Menyanthes trifoliata) lying under water in a state of decay. The 
cinnamon-coloured receptacles of Lenzites sepiaria only grow from prostrate 
trunks of conifers, and the black fuliginous fructifications of Bulgaria polymorpha 
only on those of oaks. A small discoid fungus named Poronia punctata, white 
with black spots on the top, is only found on cow-dung; another fungus, @ymnoaseus 
uneinatus on that of mice, and Otenomyces serratus on decaying goose feathers. 
That many mosses are also very fastidious in the selection of their substratum 
has already been intimated. Just as in the Alps Splachnum ampullaceum is only 
found growing on the putrefying dung of cattle, so in arctic regions the splendid, 
large-fruited Splachnwm luteum and S. rubrwm occur exclusively on that of rein- 
deer. Tetraplodon wrceolatus is met with on mountains always with decaying 
excrements of chamois, goats, or sheep for a substratum, whilst Tetraplodon 
angustatus chooses the excrements of carnivorous animals, and Tayloria serrata 
is only seen near cow-chalets on decomposing human feces. The circumstances 
of the occurrence of another moss belonging to the Splachnacex, ze. Tayloria 
Rudolfiana is also very interesting. It grows usually on the branches of old 
trees, especially maples in sub-alpine regions, and one is tempted to believe that in 
respect of its nutrient substratum it is an exception to the rule of the rest of the 
