(6) The hyphae from the ascogonial cells spread out in a complex layer at the base of the hymenium, and send up branches which form the asci, either, as in most Ascomycetes, from the penultimate cell of the fertile branch, or from the last cell, as in _Sphyridium_ (_Baeomyces rufus_)[575] and in _Baeomyces roseus_. The same variation has been observed in fungi—in a species of _Peziza_[577], in which it is the end-cell of the branch that becomes the mother-cell of the ascus; but this deviation from the normal is evidently of rare occurrence either in lichens or fungi. _d._ HYPOTHECIUM AND PARAPHYSES. The hypothecium is the layer of hyphae that subtends the hymenium, and is formed from the complex of hyphae that envelope the first stages of the carpogonia. It is vegetative in origin and distinct from the generative system. In lichens belonging to the Collemaceae, the paraphyses rise from the branching of the carpogonial stalk-cell immediately below the ascogonium[578], but have no plasma connection with it. They are thus comparable in origin with the paraphyses of many Discomycetes. In several genera in which the algal constituents are blue-green, such as _Stictina_, _Pannaria_, _Nephroma_, _Ricasolia_ and _Peltigera_, Sturgis[579] found that reproduction was apogamous and also that asci and paraphyses originated from the same cell-system: a tuft of paraphyses arose from the basal cell of the ascus, or an ascus from the basal cell of a paraphysis. These results are at variance with those of most other workers, but the figures drawn by Sturgis seem to be clear and convincing. Again in _Usnea barbata_, as described by Nienburg[580], the ascogonial cells, after the disappearance of the trichogyne, branch profusely not only upwards towards the cortex but also downwards and to each side. The upward branches give rise normally to the asci, the lower branches produce the subhymenium and later the paraphyses, and the two systems are thus genetically connected, though they remain distinct from each other, and asci are never formed from the lower cells.