Studies on the thermal-flora of Japan. XVII. Bacteria and Algae of Hot Springs in Toyama Prefecture. Toyama Prefecture, located in the northern part of the central district of the main island, has many hot springs in its mountainous region, especially in the eastern part. In the valley of the Kurobe there are Unazuki, Kuronagi, Hutami, Kinsyu, Kaneturi and Babadani spas. To the north east of Unazuki lies Ogawa spa. Among the Tateyama-mountains there are Tateyama and several other unnamed hot springs. Yamada, Yudani and Oomaki spas are situated in the western part of the prefecture. this paper reports the thermal vegetation of these hot springs except Kinsyu, where we could not observed any thermal plant. Several vials containing useful materials were collected by Prof. G. Koidzumi of Kyoto Imp. Univ. and Mr. T. Otaya and were offered to our collections (July, 1940 and October, 1941). Our researches show 51 microorganisms in all, including 4 Bacteria, 38 Cyanophyccae, 2 Chlorophyceae, 3 Congugales and 4 Bacillariophyceae. The systematic list and the thermal distribution of these plants were given in the preceeding pages. The occurrence of Cyanophyceae was most abundant, especially species of Oscillatoriaceae. Lyngbya showed only small development and their occurrence was restricted to the hot springs in Mt. Tateyama. Chlorophyceae and Conjngales were rarely observed. Bacillariophyceae were occassional except Achnanthes exigua, which developed rather extensively. The important and typical thermal representatives in the present investigation were Synechococcus elongatus v. amphigranulatus, Mastigocladus laminosus and Phormidium laminosum. The total range of temperatures was from 20-79℃. the highest temperature limit was noticed in the case of Bacteria in Babadani spa. For Cyanophyceae the highest temperature limit was 63.5℃, which was observed at Tateyama spa. Here Synechococcus elongatus v. amphigranulatus as growing abundantly, mingled with Cyanidium caldarium. For Chlorophyceae and Conjugales the limit was 38.5℃, and for Bacillariophyceae, 43.1℃. Many cool water forms, sucn as Synechococcus aeruginosus, Pleurocapsa minor, Microchaete tenera, Cylindrospermum maius, Phormidium autumnale, Microspora tumidula, Closterium moniliferum, Navicula cryptocephala, etc. were found in tepid and warm water. the total range of pH was form ca. I.o to 8.4. In the strong acid water of pH ca I.o to 2.9 occurred only Bacteria. the algal growth was found to be from pH 6.3 ot 8.4. It is noticeable that Cyanidium caldarium, which grows usually in acid water, was found in a hot water of pH 7.5. By the present investigation 14 algae are newly added to the japanese thermal flora. They are as follows : Chlorogloea microcystoides, Xenococcus alpinus, Mastigocladus laminosus v. anabaenoides, Microchaete tenera, Cylindrospermum maius, Nostoc muscorum, Oscillatoria neglecta, Phormidium Retzii, Lyngbya aerugineo-coerulea, Microcoleus vaginatus, Stichococcus subtilis, Microspora tumidula, Closterium moniliferum and Rhopalodia gibberula v. van Heurckii. Among these, Xenococcus alpinus is described as new to science. (Bot. Inst., Peers' College and Kyoto Imp. Univ.)

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