. Laboratory work in bacteriology. Bacteriology. FORM AND CLASSIFICATION OF BACTEBIA. 21 glucose, or an acid, or alkaline reaction likewise may affect the appearance of the cell. A comparison of the growths on solid and on liquid media will show peculiarities and modifications in the form and size of a given species. Thus, single cells or at most short threads may predominate on solid media, whereas in liquid media very long threads or filamentous growths may be found. The temperature exerts a profound effect upon the form characteristics of bacteria. At low temperature the growth is slower, a
. Laboratory work in bacteriology. Bacteriology. FORM AND CLASSIFICATION OF BACTEBIA. 21 glucose, or an acid, or alkaline reaction likewise may affect the appearance of the cell. A comparison of the growths on solid and on liquid media will show peculiarities and modifications in the form and size of a given species. Thus, single cells or at most short threads may predominate on solid media, whereas in liquid media very long threads or filamentous growths may be found. The temperature exerts a profound effect upon the form characteristics of bacteria. At low temperature the growth is slower, and hence the individual cell may attain an unusual size, whereas at a higher temperature multipli- cation results so rapidly that the cells are considerably smaller. Under unfavorable conditions of soil or temperature certain bacteria will show remarkable variations from the normal type. What is ordinarily a perfect rod becomes distorted out of all semblance to the original form. Club- shaped, spindle-shaped, dumb-bell-like forms are produced. Sometimes they become twisted into irregular, spherical bodies. These peculiar, deformed cells are Considered as degenerations. They are commonly designated as involu- tion forms: The organism is struggling for existence under adverse conditions which, if they persist, will eventually cause its destruction. Transplantation to a favorable medium will promptly restore the typical Fig. 3. Involution forms. The alterations mentioned above are the result of environment. Whatever may be the variation, it is to be considered always as temporary, inasmuch as the typical. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Novy, Frederick George, 1864- . Ann Arbor [Mich. ] G. Wahr
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