SAPROPHYTES AND THEIR RELATION TO DECAYING BODIES. 101 



combustible bodies arising from the dissolution of organic matter. Even the acid 

 formerly designated by Berzelius by the name of "spring-acid", is doubtless a pro- 

 duct of the decay of fragments of plants in the place where the water of the spring 

 collects. So also is humic acid, a compound produced by decay. The nature of 

 this acid is not yet, it is true, thoroughly known, and it may be a mixture of several 

 acids. We know, however, that it is easily soluble in water, and that it forms 

 soluble compounds with alkalies. Brooks running through woods or meadows, 

 small mountain lakes adjoining peat-beds, and pools in actual peat, consist of 

 water, brown in colour, which gives an acid reaction, and contains invariably 

 organic substances in solution. 



The following observations are of great interest in connection with this subject. 

 In the salt-mine at Hallstatt (Upper Austria) one of the galleries, which is hewn 

 through rock and contains no wood-work of any kind, exhibited (spread out upon 

 its smooth limestone roof) the mycelium of a fungus (an Omphalic/,), which 

 certainly required organic nutriment. There were no decaying animal or vegetable 

 remains anywhere in the gallery, and the mycelium derived nourishment solely 

 from water oozing from above through a few narrow cracks in the stone whereby 

 the surface of the latter was kept moist. This water came from a meadow lying 

 high above the mine. Between the two was a thick stratum of limestone with 

 a deep layer of earth resting upon it. The water was clear and colourless, and 

 contained a certain amount of lime, but no perceptible trace of organic substances. 

 Yet this water must have brought organic matter from the meadow above into the 

 mine, and the minute quantity so introduced sufficed to enable the fungus mycelium 

 to grow luxuriantly. 



In the Volderthal, near Hall, in Tyrol, there is a spring of cold clear water 

 rising out of slate at a height of 1000 metres above the sea-level, which is filled 

 at its source with a dark thick felt. The felt may be lifted out in pieces the size 

 of one's hand, and it is the mycelium of a fungus, probably a Pezisa. It clings 

 to slabs of slate, between which the water trickles abundantly, and its nutriment 

 can only be derived from this water. There are pine-woods and meadows in 

 the neighbourhood, but no greater amount of vegetation, humus, or rotten timber 

 than is found near other springs. 



These instances satisfactorily prove that even the clearest mountain springs 

 contain organic substances in quantities sufficient, however minute, to nourish 

 fungi. When the origin of springs is taken into account, this result is not really 

 surprising. They are fed by deposition from the atmosphere. The water thus 

 deposited percolates into the ground, passing, in the first place, through a layer of 

 earth-mould which is covered by vegetation, and contains more or less humus in its 

 upper strata. A small quantity of the products of decay is inevitably absorbed, 

 and even if they are partially withdrawn again in lower strata of the earth, traces 

 are still retained by the water in its descent to greater depths, and re-ascent to the 

 surface in the form of springs. The characteristics of the great veins of water 

 which ascend in this way are no doubt common to the smaller veins which originate 



