Page:Bergey's manual of determinative bacteriology.djvu/282

 at the middle of the concavity. The so-called nuclear body shows plainly in the electron micrographs. Source: Isolated from the buccal cavity of man. Habitat: Found in the buccal cavity.

3. Selenomonas ruminantium (Certes, 1889) Wenyon, 1926. {Ancyromonas runiinan- tium Certes, Bull. Soc. Zool., France, H, 1889, 70; Selenomastix ruminantium Wood- cock and Lapage, Quart. Jour. Micro. Sci., 59 (N.S.), 1913-1914, 433; Wenyon, Proto- zoology. 1, 1926,311.) ru.mi.nan'ti.um. L. part. adj. ruminans, ruminantis ruminating; M.L. neut.pl.n. ruminantia ruminants; M.L. pi. gen. noun ruminantium of ruminants. Rigid, crescent-shaped cells which meas- ure 2 to 3 by 9.5 to 11 microns. Woodcock and Lapage {op. cit., 434) state that the cells are only slightly crescentic and never assume the S shape as reported by Certes (op. cit., 439); furthermore, they report that the curve lies in but one plane. A tuft of flagella which attains a length of 8.0 to 9.5 microns springs from the center of the concavity. The protoplasm stains homogeneously ex- cept at the base of the flagella where a deepl}^ staining mass is easily demonstrable. Reproduction is by binary fission transverse to the long axis of the cell and through the flagellar region. Each half of the flagella passes to one of the two pear-shaped daugh- ter cells where it is attached near the blunt end; later the flagella undergo an apparent shift in position to the center of the con- cavity. Probably anaerobic but does not grow on ordinary media either aerobically or an- aerobically. Woodcock and Lapage (op. cit., 445 ff.) found ellipsoidal, non-motile organisms mixed abundantly with the motile crescents and felt that these might represent a stage in the life history of the crescents although they could not demonstrate this. Wenyon {op. cit., 311) also thinks that a rounded flagellate organism may be a stage of the crescent-shaped organism, but he presents no proof to support this conclusion. Source: Found by Certes {op. cit., 70) by microscopical examination of rumen juice of cattle, sheep and deer. Later found by Woodcock and Lapage {op. cit., 433) very abundantly in the rumen juice of goats. Habitat : Found as a predominant organ- ism on microscopical examination of rumen juices from herbivorous mammals.

My.co.nos'toc. Gr. noun myces fungus; M.L. neut.n. Nostoc a genus of algae; iLL. neut.n. Myconostoc fungus nostoc.

Curved, colorless cells occurring singly or in curved or spiral chains. Embedded in small, spherical, gelatinous masses. Found in fresh- or sulfur-water containing decomposing organic matter.

The type species is Myconostoc gregarium Cohn.

1. Myconostoc gregarium Cohn, 1875. (Cohn, Beitrage z. Biol. d. Pflanzen, 1, Heft 3, 1875,_ 183; Spirosoma gregarium Migula, Syst. d. Bakt., ^, 1900, 960.) gre.gar'i.um. L. adj. gregarius of or be- longing to a flock or group. Cells curved to comma-shaped, 1 by 5 to 10 microns, often joined together as spiral chains which may resemble horse-shoes or which may twist around each other to form coiled, non-septate, non-motile, colorless filaments. The filaments are usually en- closed in a spherical, solid, microscopic, gelatinous mass which measures 10 to 17 microns in diameter; these masses may clump together and form a cluster, usually on the surface of the water, which is visible to the naked eye. Excellent illustrations de- picting the nature of this species are shown in Zopf (Die Spaltpilze, 3 Aufl., 1885, 23).