_a._ OPEN OR CLOSED APOTHECIA. Schwendener[657] drew attention to two types of apothecia directly influenced by the thallus: those that are closed at first and only open gradually, and those which are, as he says, open from the first. The former occur in genera and species in which the thallus has a stoutish cortex, as, for instance, in _Lobaria_ where the young fructification has all the appearance of an opening perithecium. The open apothecia (_primitus aperta_) are found in non-corticate lichens, in which case the pioneer paraphyses arrive at the surface easily and without any converging growth. Similar apothecia are borne directly on the hypothallus at the periphery, or between the thalline areolae, and they are also characteristic of thin or slender thalli as in _Coenogonium_. In both types of apothecium, the paraphyses pierce the cortex (Fig. 100) and secure the emergence of the developing ascomata. [Illustration: Fig. 100. _Physcia ciliaris_ DC. Vertical section of apothecium still covered by the cortex. _a_, paraphyses; _b_, hypothecium; _c_, gonidia of thallus and amphithecium. × 150 (after Baur).] _b._ EMERGENCE OF THE ASCOCARP. Hue[658] has taken up this subject in recent years and has described the process by which the vegetative hyphae surrounding the fruit primordium, excited to active growth by contact with the generative system, take part in the later stages of fruit formation. The primordium generally occupies a position near to, or just within, the upper medulla, and the hyphae in contact with it soon begin to branch freely in a vertical direction, surrounding the developing fruit and carrying it upwards generally to a superficial position. The different methods of the final emergence give two very distinct types of mature apothecium: the _lecideine_ in which the gonidial zone takes no part in the upward growth, and the _lecanorine_ into which the gonidia enter as an integral part. In the lecideine series (Fig. 101) the encircling hyphae from the upper medulla rise as a compact column through the gonidial zone to the surface of the thallus; they then spread radially before curving up to form the outer wall or “proper margin” round the spore-bearing disc. The branching of the hyphae is fastigiate with compact shorter branches at the exterior. In such an apothecium gonidia are absent both below the hypothecium and in the margins. [Illustration: Fig. 101. _Lecidea parasema_ Ach. Vertical section of thallus and apothecium with proper margin only × ca. 50.]