. Elementary text-book of zoology, general part and special part: protozoa to insecta. Animals. 206 PBOTQZOA. 1. The Schizvmijetiiaa;* (Bacteria) arc small globular or rod-shaped bodies which are found in decaying matter, and are especially numerous on the surface of putrefying fluids, where they give rise to a slimj' film (fig. 148). They are most nearly allied to the fungus of yeast, with which they also agree in their manner of nourishment, in that they make \ise of ammonia and organic com- pounds containing carbon. Like the yeast fungus they excite and maintain the fermentation or, as may
. Elementary text-book of zoology, general part and special part: protozoa to insecta. Animals. 206 PBOTQZOA. 1. The Schizvmijetiiaa;* (Bacteria) arc small globular or rod-shaped bodies which are found in decaying matter, and are especially numerous on the surface of putrefying fluids, where they give rise to a slimj' film (fig. 148). They are most nearly allied to the fungus of yeast, with which they also agree in their manner of nourishment, in that they make \ise of ammonia and organic com- pounds containing carbon. Like the yeast fungus they excite and maintain the fermentation or, as may happen, putrefaction of organic matter by with- drawing its oxygen or by attracting oxygen from the air (reduction or oxyda- tion ferments). But they are clearly separated from the fungi by their deve- lopment, for thcij iiicrraxe hij dicliViiig into two halrrn, while the yeast fungus {Saccharonijiccs. Uormincium) forms buds which separate off as spores. The transverse division takes place, after the cell has become elongated, by a con- striction of the protoplasm and by the secretion of a cross partition wall. The daughter-cells either divide at once, or remain united and produce chains of Bacteria (filiform Bacteria) by afresh fission. Sometimes the successive genera- tions of cells remain connected by a gelatinous substance, and so produce irre- gular shaped gelatinous masses izoogloea'). Sometimes they become free and are dispersed in swarms. They may also settle on the bottom in the form of a. Fig. 118.—Scliizomycetes (after F. Cohn). a, Micrococcus, b. Bacterium termo, bacteria of putrefying fluids, both in the motile and zoogloea form. granular precipitate, as soon as the nourishment in the fluid is exhausted. The greater number have a motile and a motionless stage ; in the first they rotate themselves about their long axis, but are also able to bend and extend, but never to serpentine. Their activity seems to be connected with the presence of oxygen. Owing to the abse
Size: 2416px × 1034px
Photo credit: © Paul Fearn / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectanimals, bookyear1892
