of the two nuclei was followed by the enlargement of the ascus and the subsequent nuclear division for spore formation. In the first heterotypic division twelve chromosomes, double the number observed in the vegetative nucleus, were counted on the equatorial plate. In the third division they were reduced to the normal number of six, from which F. Bachmann concludes that a twofold fusion must have taken place—in the ascogonium and again in the ascus. Spiral or coiled ascogonia were observed by Wainio[557] in the gelatinous crustaceous genus _Pyrenopsis_, but the trichogynes did not reach the surface. In _Lichina_[558], a maritime gelatinous lichen where the carpogonia occur in groups, trichogynes have not been demonstrated. A peculiarity of some gelatinous lichens noted by Stahl[559] and others in species of _Physma_, and by Forssell[560] in _Pyrenopsis_ and _Psorotichia_, is the development of carpogonia at the base of, and within the perithecial walls of old spermogonia. No special significance is however attached to this phenomenon, and it is interesting to note that a similar growth was observed by Zukal[561] in a pyrenomycetous fungus, _Pleospora collematum_, a harmless parasite on _Physma compactum_ and other Collemaceae. The structures invaded were true pycnidia of the fungus as the minute spores were seen to germinate. A “Woronin’s hypha” at the base of several of these pycnidia developed asci which pushed up among the spent sporophores. _b._ CARPOGONIA OF NON-GELATINOUS LICHENS. The soft loose tissue of the gelatinous lichens is more favourable for the minute study of apothecial development than the closely interwoven hyphae of non-gelatinous forms, but Borzi[562] had already extended the study to species of _Parmelia_, _Anaptychia_, _Sticta_, _Ricasolia_ and _Lecanora_, and in all of them he succeeded in establishing the presence of ascogonia and trichogynes. After him a constant succession of students have worked at the problem of reproduction in lichens. Lindau[563] published results of the examination of a considerable series of lichens. In _Anaptychia_ (_Physcia_) _ciliaris_, _Physcia stellaris_, _Ph. pulverulenta_, _Ramalina fraxinea_, _Placodium_ (_Lecanora_) _saxicolum_, _Lecanora subfusca_ and _Lecidea enteroleuca_ he demonstrated the presence of ascogonia with trichogynes. In _Parmelia tiliacea_ and in _Xanthoria parietina_ he found ascogonia but failed to see trichogynes. In none of the species examined by him did he observe any fusion between the trichogyne and a spermatium.