The Hot Springs of Yunokawa lies on the right bank of the river Matukura, in the eastern suburbs of the city of Hakodate. Its thermal flora was surveyed on July 25, 1938 and five species of Chanophycean algae were found. They are as follows : (1) Mastigocladus laminosus COHN. Temp. 45,5℃, pH 7,2. (2) Oscillatoria amphibia AG. Crass. trich. 1,5-2,3 μ ; long. cell. 3-6 μ. Floating on the surface or submerged on the bottom of the hot water. Temp. 42,5℃, pH 7,3. (3) Oscillatoria acuminata GOM. Crass. trich. 3-5 μ ; long. cell. 5-7 μ. Forming soft gelatinous mass on the bottom of water. Temp. 43,2℃, pH 7,5. (4) Oscillatoria brevis KUTZ. Crass. trich. 3,5-6 μ ; long. cell. 2,5-5 μ. Submerged on the bottom in slowly flowing warm water. Temp. 41,2℃, pH 7,4. (5) Phormidium laminosum (AG.) GOM. Temp. 45,5℃, pH 7,2. Occurring mixed with Mastigocladus laminosus. The Hot Springs is on the opposite bank of Yunokawa. Collections were made on July 26, 1938. The thermal algae found are as follows. Cyanophyceae : (1) Synechococcus elongatus NAG. var. vestitus COPELAND. Crass. cell. 2-2,7 μ ; long. cell. 4-9 μ. Temp. 38,2-48℃, pH 7,3-7,4. (2) Oscillatoria amphibia AG. Crass. trich. 1,5-2,5 μ ; long. cell. 2,5-6 μ. Temp. 53,2-58℃, pH 7,5-7,6. (3) Oscillatoria angustissima W. et G. S. WEST. Crass. trich. 0,6 μ ; long. cell. 1 μ. Among filaments of other species of Oscillatoria. Temp. 32℃, pH 7,3. (4) Oscillatoria Okeni AG. Crass. trich. 8-9 μ ; long. cell. 3-4,5 μ Temp. 32℃, pH 7,3. (5) Oscillatora Agardhii GOM. Crass. trich. 3,5-4,5 μ ; long. cell. 2,2-3 μ Small specimens. Mixed witth Oscillatoria Okeni and O. angustissima. This plant is usually known as plankton algae. Temp. 32℃, pH 7,3. (6) Phormidium laminosum (AG.) GOM. Temp. 38,2℃, pH 7,3.
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