CARPOSPOREM. 307 



of an angiocarpous fructification a peculiarly formed mass of tissue in which very 

 large numbers of spores are produced, such a mass is termed a nucleus or gleba. 



The sexual organs, so far as they are known among the Ascomycetes, consist 

 of a carpogonium as the female, and of a so-called pollinodium (antheridium) as the 

 male. The two organs may differ but little in size and shape, and in Gymnoascus 

 they are quite similar ; more commonly, however, the carpogonium is larger and is 

 multicellular, whereas the pollinodium is a thin, usually branched, tubular cell. In all 

 cases the carpogonium differs from the pollinodium in that from it alone the fertile 

 hyphse take origin from which the spores are finally developed, the sterile tissue 

 being derived from the hyphse bearing the carpogonium or even from neighbouring 

 cells. 



Fertilisation is never affected by means of antherozoids ^ but by the close appli- 

 cation of the pollinodium in its whole length to the carpogonium, or merely of the 

 apex of the pollinodium to the anterior portion of the carpogonium. Occasionally 

 this portion of the carpogonium is prolonged into a narrow tube like the trichogyne 

 of Nemalion. In the majority of the observed cases there is no direct exchange of 

 protoplasmic substance between the pollinodium and the carpogonium in the process 

 of fertilisation : the two organs remain closed and the fertilising matter passes from 

 the pollinodium into the carpogonium apparently by diffusion. The fertile hyphse 

 of the fructification arise usually not from that part of the carpogonium which has 

 been in direct contact with the pollinodium, but from nearer its base. Here again an 

 analogy with the formation of the fructification of Florideae presents itself. 



Histologically considered, the mycelium and the fructification of these Fungi 

 consist of hyphae. The hypha? are multicellular, usually much-branched, filaments 

 which grow at their apices, and are generally very long and thin. In many cases, 

 even in the larger fructifications, as for instance in the Mushrooms, it is easy to 

 make out the individual hyphse, but in other cases, although the tissue really consists 

 of hyphae, a so-called pseudo-parenchyma is formed by the close aggregation of their 

 short thick segments. In angiocarpous Fungi (Tuberaceae, Gasteromycetes) this 

 pseudo-parenchyma is usually differentiated into well-defined concentric layers. 

 Commonly, but not universally, the cell-walls of the pseudo-parenchyma are not 

 coloured blue when treated either with iodine alone, or with iodine and sulphuric 

 acid, but in certain cases this colouration is produced by the action of iodine alone 

 (Asci of Lichens). Starch, as also chlorophyll, is absent from all Fungi, and this is 

 the more remarkable since starch is found in Phanerogams which possess no 

 chlorophyll. 



Fungi grow exclusively upon organic substrata. Many grow in earth which is 

 rich in humus or some other organic matter, others are parasitic upon and within 

 animals and plants; this parasitism may present itself in the most varied manner, 

 the most remarkable case being perhaps that which, as we shall hereafter see, occurs 

 among Lichens. The mycelium usually buries itself in the nutrient substratum and 

 can scarcely be separated from it, whereas the fructification comes to the surface. 



As I do not propose to give an exact systematic account of the innumerable 



^ [In Lichens the carpogonium is fertilised by non-motile antherozoids, termed spermatia, 

 which resemble those of the Florideae,] 



X 2 



