RELATIONS OF SAPROPHYTES TO THEIR NUTRIENT SUBSTRATUM. 117 
part microscopic, all of which cannot be classed as saprophytes, but which, in order 
to be able to thrive in the tracks of trickling water, must have the capacity of 
surviving desiccation for weeks, and even months, on the barren rock after having 
been previously supplied with copious moisture for a time. In the case of lichen- 
growths in particular these are very favourite sites; and when the lichens cover 
a large area they attract one’s attention from afar. In limestone ranges, the 
light-gray rock of steep declivities, interrupted by ledges covered with grass and 
low brushwood, is extensively coloured by dark vertical bands and streaks, and the 
effect is the same as if a dye had flowed from the ledges over the face of the rock. 
These dark streaks indicate the course of the water which oozes from the humus 
and renders possible the existence of numberless minute plants on the precipitous 
face, in particular several dark crustaceous lichens (Acarospora glaucocarpa, 
Aspicilia flavida, Lecidea fuscorubens, Opegrapha lithyrga, &e.). 
The quantity of organie compounds brought down in solution by the water 
which filters from the layers of humus on rocky ledges, and that which trickles 
down the bark of trees, is, however, very small. Still, it is amply sufficient to 
meet the requirements of the plants occurring at the spots in question. The claims 
made by them upon their nutrient source are very moderate. We may here recall 
the instances previously mentioned of mycelia of fungi which have been found 
satisfied with the scarcely perceptible quantities of organic compounds in water 
filtering into the shaft of a mine, and in the pure water of a mountain spring 
respectively. To these instances must here be added the production of mycelia 
in the wooden pipes through which the clear water of mountain springs is con- 
veyed. After these pipes, which are made from the trunks of pines, have been 
used as conduits for years, and their inner layers of wood have long since been 
washed out, the mycelium of the fungus Lenzites sepiaria is not. infrequently 
developed within them, and in such luxuriance, indeed, that it forms great yellowish- 
gray floceulent masses, which issue from the pipe’s inner surface, and float in the 
stream of running water. In time these floceulent masses increase in the clear 
spring-water to such a degree that the pipes become completely blocked, and the 
flow of water is arrested. And yet the water conducted through the pipes is so 
pure, where it enters into and issues from them, that the residue obtained by the 
evaporation of hundreds of litres afforded no trace of any organic matter. 
Seeing that most saprophytes absorb only such a comparatively small amount 
of organic matter, one is all the more surprised to notice that a large number of 
them fall suddenly, at certain times, into the opposite extreme. People speak of 
things rapidly produced in abundance as “ mushroom-growths”, and as “shooting up 
like fungi”. The fructifications of many fungi are in fact developed with a rapidity 
which borders on the miraculous. The various species of Coprinus living on dung 
produce their long-stalked, cap-shaped fructifications during the night, and by the 
evening of the next day the caps have already fallen to pieces, and are in a state 
of decomposition, and nothing is to be seen in their place but a black deliquescent 
mass like a blot of ink. The weight of this fructification, thus matured within 
