FUNGI. 239 



another ; it never attains that differentiation into axes and dissimilar lateral leaf-like 

 appendages which occurs in many Algce. IMuch more common than ramification 

 is, moreover, the tendency of the larger Fungi to the formation of compact roundish 

 masses of tissue, in the interior of which a differentiation takes place into different 

 layers and masses of tissue for the purpose of reproduction. Among the Gastero- 

 mycetes structures unknown elsewhere in the vegetable kingdom and often highly 

 curious are produced at the time of the ripening of the spores and for the 

 purpose of their dissemination {e. g. Clathrus, Phallus, Geaster, Crucibulum) by 

 the extension of inner masses of tissue, and by the deliquescence of certain 

 portions of them and the rupture of outer layers (Peridia). 



The whole process of development of a Fungus, whether it consists of a 

 single branched hypha or of an aggregation of hyphae, may be divided into two 

 periods; — from the spore a Mycelium is first of all produced directly, or through 

 the intervention of a Pro-mycelium ; from this the reproductive receptacles after- 

 wards grow. 



The Mycelium, developed from the germinating filaments, and becoming 

 very much branched, creeps in or upon the substratum which nourishes it, out 

 of which it assimilates the useful materials. It usually consists of filaments 

 simple or associated into the form of a pellicle (as Penicillium on fluids). In the 

 Fungi with large compact receptacles, the mycelium often consists of thicker bundles 

 each of which is composed of a number of parallel hyphae (as in Phallus, Sphaero- 

 bolus, Agaricus, &c.). The branches of the mycelium not unfrequently anastomose 

 among one another ; if simple by a kind of conjugation of one hypha with another. 

 These mycelia can live for a shorter or longer time (often for years) ; they may pro- 

 duce reproductive receptacles only once or repeatedly (/. e. may be monocarpous or 

 polycarpous). In the Haplomycetous forms the receptacles are simple branches of the 

 hypha3, which often arise from the substratum ; in the rest of the class they appear 

 as spherical aggregations of the branches of the mycelium at definite points, which 

 then develope further independently in the most various ways, either remaining in 

 the substratum (as in the truffle), or growing up above it. In some cases the young 

 receptacle again puts out hyphae, which, penetrating the substratum, form a 

 secondary mycelium. 



A peculiar form of the mycelium occurs in the Sclerotia, which were at one 

 time considered as a special section of independent forms of Fungi. They form 

 tuberous substances, and are not peculiar to any particular group of Fungi, but occur, 

 in accordance with specific modes of life, in species of the most different groups, 

 like bulbs and tubers among Phanerogams. The sclerotia arise out of ordinary 

 mycelia by a dense interweaving of the hyphae; they are hard bodies of definite 

 form, the outer layer of which, mostly developed as pseudo-parenchyma, forms a 

 kind of shell or skin. They are found, according to the habitat of the Fungus, on 

 the surface or in the interior parts of other plants, as fallen leaves, or in the ground, 

 and go through a period of rest, after which they produce receptacles and disappear, 

 these latter being nourished from their substance. 



If the Receptacle which proceeds from the mycelium consists of a simple or 

 branched hypha, this latter bears, at the end of its ramifications, the spores, or, 

 according to circumstances, the sexual organs. If the receptacle is composed of a 



