ondary cysts 10 to 12 microns. The Krzemie- niewskis (Acta Soc. Bot. Poloniae, 5, 1927, 96) recognize a variety, Sorangium septatum var. microcystum, which has secondary cysts with dimensions 3 to 8 by 4 to 10 microns. Source: Collected twice from horse dung in Cambridge, Mass. Habitat: Found on decaying organic mat- ter in soil and in the dung of various ani- mals. Reported by Krzemieniewski {loc. cit.) as common in Polish soil. Illustrations: Thaxter (op. cit., 1904, PI. 27, Figs. 25-28), Jahn (Kryptogamen-flora d. Mark Brandenburg, V, Pilze I. Lief 2, 1911, 202, Fig. 2) and Krzemieniewski (Acta Soc. Bot. Poloniae, 4, 1926, PI. 27, Figs. 27- 38; also see ihid., 1927, PI. V, Fig. 15, var. microcystum, Fig. 16). 6. Sorangium coniposituni (Thaxter, 1904) Jahn, 1924. {Polyangium compositiim Thaxter, Bot. Gaz., 37, 1904, 413; Jahn, Beitriige zur bot. Protistologie. I, Die Poly- angiden. Geb. Borntraeger, Leipzig, 1924, 74; Polyangium sorediatum Quehl, Cent. f. Bakt., II Abt., 16, 1906, 17; not Polyangium sorediatum Thaxter, op. cit., 1904, 414.) com.pos'i.tum. L. adj. compositus com- pound. Vegetative cells: Not described. Fruiting bodies: Dull yellowish orange changing to dark red on drying. Rounded, small, 0.5 to 1 mm, usually as a whole or even in larger clumps surrounded by a deli- cate and evanescent membrane. In large fruiting bodies the cysts are bound together in balls, 70 to 90 microns in diameter, by a delicate membrane. The balls readily fall apart. Secondary cysts are angular, 7 by 11 microns, surrounded by a delicate orange- red membrane about 0.4 micron in thick- ness. Length of rods in the cysts, 5 microns. Source : Found on rabbit dung from South Carolina. Jahn (op. cit., 1904) found it four times on rabbit dung near Berlin, twice on hare dung in Oberharg. Habitat: Found on decajang organic mat- ter in soil and in the dung of various ani- mals. Common in soils of Poland according to Krzemieniewski (Acta Soc. Bot. Pol- oniae, 5, 1927). Illustrations: Thaxter (op. cit., 1904, PI. 27, Figs. 29-30), Jahn {pp. cit., 1924, PI. I, Fig. 6) and Krzemieniewski {op. cit., 4, 1926, PI. Ill, Figs. 32-36; ibid., 5, 1927, PI. IV, Figs. 7-12; PI. V, P^igs. 13-14; PI. VI, Fig. 36). 7. Sorangium nigrum Krzemieniewska and Krzemieniewski, 1937. (Bull. Int. I'Acad. Pol. Sci. et Lettres, Classe Sci. Math, et Nat., Ser. B, 15, 1937.) ni'grum. L. adj. niger black. Vegetative cells: 1.1 to 1.3 by 2.5 to 5.5 microns. Fruiting body: Primary cysts generally not formed; when observed, appeared as smoke-colored slime envelope surrounding clumps of a few cysts. Secondary cysts usu- ally arranged in rows within cellulose fibers, the material of the fiber forming a common sheath. Each individual cyst is enclosed by a cyst wall, clearly differentiated from the tubular-shaped cellulose fibers. Cysts meas- ure 9 to 16 by 9 to 23 microns; average 10 by 18 microns. Cyst wall moderately thick, colorless, transparent, becoming light brown with age, and finally black. Colonies: Young colonies are black in color. On filter paper a bright orange margin is noted, the vegetative cells of which cover the cellulose fibers. On cotton cloth the margin is bright, dirty yellow, tinged with pink. Under low-power magnification, center of the colony appears similar to matted fungal hyphae, due to characteristic com- pact accumulation of cysts and cellulose fibers. Physiology: Cellulose fibers become swol- len by the action of this organism and be- come gray -brown with a violet tinge. Fibers lose the properties of cellulose and give no characteristic reactions. Source: Isolated from soil. Habitat: Soil. Decomposes cellulose. Illustrations: Krzemieniewskis {ibid., Plate IV, Figs. 22-26). 8. Sorangium nigrescens Krzemie- niewska and Krzemieniewski, 1937. (Bull. Int. I'Acad. Pol. Sci. et Lettres, Classe Sci. Math, et Nat., Ser. B, 15, 1937.) ni.gres'cens. L. part. adj. nigrescens be- coming black. Vegetative cells: 1.2 to 1.4 by 2.5 to 6.4 microns. Younger cells somewhat shorter.
