The two principal parts of which an apothecium consists are the hypothecium and the hymenium, or thecium.
The hypothecium is the basal part of the apothecium on which the hymenium is borne; the latter consists of asci (thecae) with ascospores, and paraphyses.
In these forms gonidia are found in connexion with the young fruit; such algal cells undergo numerous divisions becoming very small in size and penetrating into the hymenium among the asci and paraphyses.
The two bestknown genera are Cora and Dictyonema; Corella, whose hymenium is unknown, is also placed here by Wainio.
When the fungus predominates in the thallus it has a bracket-like mode of growth and is found projecting from the branches of trees with the hymenium on the under side.
A solution of iodine is also used as a test owing to the blue or wine-red colour which the thallus, hymenium or spores may give with this reagent.
Laudatea), Corella (doubtfully placed here as the hymenium is unknown).
Here we have the cushion-like type (stroma) of Nectria and many Pyrenomycetes, the clavate "receptacle" of Clavaria, &c., passing into the complex forms met with in Sparassis, Xylaria, Polyporei, and Agaricini, &c. In these cases the compound sporophore is often termed the hymenophore, and its various parts demand special names (pileus, stipes, gills, po--es, &c.) to denote peculiarities of distribution of the hymenium owlthe surface.
In such examples as the above we may regard the hymenium (Solenia, Cyphella), zygospores, or asci as truly invested by later growth, but in the vast majority of cases the processes which result in the enclosure of the spores, asci, &c., in a "fructification" are much more involved, inasmuch as the latter is developed in the interior of hyphal tissues, which are by no means obviously homologous with a stroma.
Much more complicated are the processes in a large series of "fructifications," where the mycelium first develops a densely packed mass of hyphae, all alike, in which labyrinths of cavities subsequently form by separation of hyphae in the previously homogeneous mass, and the hymenium covers the walls of these cavities and passages as with a lining layer.
From each of the four segments in the case of Tremella a long outgrowth arises which reaches to the surface of the hymenium From Strasburger's Lehrbuch der Bolanik, by permission of Gustav Fischer.
Exobasidium) the basidia are borne directly on the ordinary mycelium, but in the majority of cases the basidia are found developed in layers (hymenium) on special sporophores of characteristic form in the various groups.
The gleba is usually differentiated into a number of chambers which are lined directly by the hymenium (basidial layer), or else the chambers contain an interwoven mass of hyphae, the branches of which bear the basidia.