A manual of hygiene and sanitation / By Seneca Egbert.

  • Egbert, Seneca, 1863-1939.
Date:
[1907], [©1907]
Catalogue details

Licence: Public Domain Mark

Credit: A manual of hygiene and sanitation / By Seneca Egbert. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

    37/500 (page 41)
    Accordingly as they live best with or without air or oxy- gen they are aerobic or anaerobic. Again, they may be named according to their product—e. g., some produce colors, chromogenic; others pus, pyogenic, etc. Lastly, they exist and grow either as saprojihytes upon dead, or as parasites upon living organic matter. We also say that an organism is opdional or facultative when it is at one time a saprophyte and at another a parasite, or at one time aerobic and again anaerobic; and that it is obligate when it has not this property of changing its nature according to surrounding conditions. Some of the micrococci are named according to the manner in which they grow. If in pairs, they are called dijjlococci; in fours, tetracocci; in threads, streptococci, etc. Groups or masses of micrococci or bacilli held to- gether by a gelatinous substance are called zobglea. As compared with other bacteria, with one or two exceptions, we know but little about the spirilla. The germ of cholera—the comma bacillus (?)—belongs to this class, and the cause of relapsing fever is also probably a spirillum. Most of the bacteria thrive best in culture-media that are neutral or only slightly alkaline, though a few species seem to do better in slightly acid surroundings. So, also, they do best at temperatures ranging between 20° and 40° C. (68° and 104° F.), though they may grow at any temperature between 5° and 43° C. (41° and 109.4° F.). Any marked deviation in the culture-media from the neutral point or continued exposure to extremes of tem- perature may either check the growth of the organisms altogether, and eventually destroy them, or may cause spore-formation, or the production of involution-forms, or a change in the composition and the character of the chemical products which the l)acteria normally produce.