_c._ GERMINATION OF SPERMATIA (pycnidiospores). The strongest argument in favour of regarding the spermatia of lichens as male cells had always been the impossibility of inducing their germination. That difficulty had at length been overcome by Möller[727] who cultivated them in artificial solutions, and by that means obtained germination in nine different lichen species. He therefore rejected the commonly employed terms spermatia and spermogonia and substituted pycnoconidium and pycnidia. Pycnidiospore has been however preferred as more in accordance with modern fungal terminology. His first experiment was with the “spermatia” of _Buellia punctiformis_ (_B. myriocarpa_) which measure about 8-10 µ in length and about 3 µ in width, and are borne directly on the septate spermatiophores (arthrosterigmata). In a culture drop, the spore had swelled to about double its size by the second or third day, and germination had taken place at both ends, the membrane of the spore being continuous with that of the germinating tube. In a short time cross septa were formed in the hyphae which at first were very close to each other. While apical growth advanced these first formed cells increased in width to twice the original size and, in consequence, became slightly constricted at the septa. In fourteen days a circular patch of mycelium had been formed about 280 µ in diameter. The development exactly resembled that obtained from the ascospores of the same species grown in the absence of gonidia. The largest thallus obtained in either case was about 2 mm. in diameter after three months’ growth. The older hyphae had a tendency to become brownish in colour; those at the periphery remained colourless. In _Opegrapha subsiderella_ the development, though equally successful, was very much slower. The pycnidiospores (or spermatia) have the form of minute bent rods measuring 5·7 µ × 1·5 µ. Each end of the spore produced slender hyphae about the fifth or sixth day after sowing. In four weeks, the whole length of the filament with the spore in the middle was 300 µ. In four months a patch of mycelium was formed 2 mm. in diameter. Growth was even more sluggish with the pycnidiospores of _Opegrapha atra_. In that species they are rod-shaped and 5-6 µ long. Germination took place on the fifth or sixth day and in fourteen days a germination tube was produced about five times the length of the spore. In four weeks the first branching was noticed and was followed by a second branching in the seventh week. In three months the mycelial growth measured 200-300 µ across.