A somewhat similar process of development is described by Sturgis[715] in the spermogonia of _Ricasolia amplissima_, in which species the primordium arises by a profuse branching of the medullary hyphae in certain areas close to the gonidial zone. The cells of these branching hyphae are filled with oily matter and gradually they build up a dense, somewhat cylindrical body which narrows above to a neck-like form. The growth is upwards through the gonidial layer, and the structure widens to a more spherical outline. It finally reaches the outer cortex when some of the apical cell membranes are absorbed and a minute pore is formed. The central part becomes hollow, also by absorption, and the space thus left is lined and almost filled with multicellular branches of the hyphae forming the wall; from the cells of this new tissue the spermatia are abstricted. _b._ FORMS AND TYPES OF SPERMATIOPHORES. The variations in form of the fertile hyphae in the spermogonium were first pointed out by Nylander[716] who described them as sterigmata[717]. He considered the differences in branching, etc. as of high diagnostic value, dividing them into two groups: simple “sterigmata” (or spermatiophores), with non-septate hyphae, and arthrosterigmata, with jointed or septate hyphae. Simple “sterigmata” comprise those in which the spore or spermatium is borne at the end of a secondary branch or sterigma, the latter having arisen from a cell of the upright spermatiophore or from a simple basal cell. The arthrosterigmata consist of “short cells almost as broad as they are long, much pressed together, and appearing almost agglutinate especially toward the base; they fill almost the whole cavity of the spermogonium.” The arthrosterigmata may grow out into the centre of the cavity as a single cell-row, as a loose branching network, or, as in _Endocarpon_, they may form a tissue filling the whole interior. Each cell of this tissue that borders on a cavity may bud off a spermatium either directly or from the end of a short process. [Illustration: Fig. 113 A. Types of lichen “sporophores” and pycnidiospores. 1, _Peltigera rufescens_ Hoffm. × 910; 2,_Lecidea (Psora) testacea_ Ach. × 1200; 3,_Cladonia cariosa_ Spreng. × 1000; 4, _Pyrenula nitida_ Ach. × 1130; 5, _Parmelia tristis_ Nyl. × 700; 6, _Lobaria pulmonaria_ Hoffm. × 1000 (after Glück).] The most important contributions on the subject of spermogonia in recent years are those of Glück[718] and Steiner[719]. Glück, who insisted on the “pycnidial” non-sexual character of the organs, recognized eight types of “sporophores” differing in the complexity of their branching or in the form of the “spores” (Fig. 113 A): 1. The _Peltigera_ type: the sporophores consist of a basal cell bearing one or more long sterigmata and rather stoutish ellipsoid spores. (These are true pycnidia.) 2. The _Psora_ type: a more elongate simple sporophore with sterigmata and oblong spores.