NATURE OF FUNGI. 38 1 



form a massive body, as every one has seen in the case of the well-known Mushroom. 

 But even in these large Fungi the mycelium, the root-like vegetative and feeding 

 organ, consists very commonly of single branched hyphse creeping in the substratum. 

 The non-botanical observer usually sees only the massive fructification of the fungus, 

 which protrudes above the substratum, because the mycelium remains hidden in the 

 substratum, or at any rate only grows out from this into the moist air under certain 

 circumstances, and is moreover only clearly visible with the microscope. So far as the 

 question of nutrition is concerned, however, it is just the knowledge of the mycelium 

 and its mode of life which is of special importance ; and what is to be said here with 

 respect to the Fungi, refers essentially only to the inycelium. 



Many Fungi are satisfied with dissolving and absorbing from their substratum 

 only so much substance as is necessary for • their nutrition, either as parasites or 

 saprophytes. Hence they usually act destructively on their substratum only to a 

 slight extent ; and even when they inhabit living plants or animals, the injury caused 

 by them is insignificant — e. g. the majority of Rust-fungi (^cidiomycetes). Others 

 grow and nourish themselves harmlessly in the tissues of higher plants, finally, how- 

 ever, when themselves producing fructification, to effect malignant destruction; as 

 Phytophihora infestans, which causes the Potato disease, and the Smut of Wheat, which 

 at last completely fills up the interior of the grains with its masses of black spores. 

 To the worst enemies of the higher plants, however, belong the tree-killing Fungi, 

 the mycelia of which nestle in the wood even of older huge trees, and not only take 

 from it the nourishment necessary for their nutrition, but decompose the masses of 

 wood until they are converted into soft spongy or powdery humous substances. 

 Even wood which has already been employed for various kinds of building, 

 &c., is destroyed by Fungi. Merulius lachrymans destroys the timber-work of 

 houses, converting it into a mass of dirt, &c. Even living animals are attacked 

 and killed by Fungi. Our house-flies are destroyed annually in autumn, with the 

 exception of a few specimens which live through the winter, by a_ fupgus {Empusa 

 Musca) which infests them ; and innumerable caterpillars are killed by Sphcerice. 

 In these cases, the whole living substance of the body of the animal is finally con- 

 verted into a mass of Fungus ; the aquatic SaprolegnicB in this way consume dead 

 insects which have fallen into the water, until only the hard chitinous covering 

 is left. 



Nevertheless, these are all only individual phenomena, in contrast to the universal 

 distribution of other Fungi wherever organic life in general is possible. One may 

 well say that if there were no Fungi, the entire surface of the earth would be covered 

 with dense layers of the bodies of plants and animals which had accumulated for 

 thousands of years ; since it is essentially the Fungi, and particularly the minute 

 forms of very simple structure, which have year by year in the course of geological 

 time decomposed the dead plants and animals and again resolved them into carbon 

 dioxide, water, and ammonia. Only where perished organisms have been protected 

 from the access of the air, which Fungi require, by being enveloped on all sides by 

 mud, or sunk in turf, etc., have their remains been preserved, or at least a great part of 

 their carbon, which could not be oxidised during intramolecular spontaneous de- 

 composition by the small quantity of oxygen contained in the organic compounds 

 themselves. This has happened in the formation of coal, and is still taking place in the 



