Identifier: hygienedentalge00turn (find matches)
Title: Hygiene, dental and general
Year: 1920 (1920s)
Authors: Turner, C. E. (Clair Elsmere), 1890-1974 Rice, William
Subjects: Hygiene Teeth
Publisher: St. Louis, C. V. Mosby
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image:
Sampling StationsYearly Averages ofNitrogen as Free nh3>Aubuminoid NH,,Nitrites,Nitrates and Total. N at Stations*? to*6 Inclusive Fig. 34.—Diagram showing the condition of the stream studied at Brockton.The chart shows the average figures ohtained from weekly analyses of the water ateach sampling station covering a full year. 238 HYGIENE: DENTAL AND GENERAL At the point where the pollution enters the stream there isa sudden increase in the number of bacteria. These breakdown the organic substances of pollution but they themselvesare used as food by protozoa which are found in great numbersjust below the place where the bacteria are most numerous.The protozoa in turn are devoured by small Crustacea andother higher animals, which are suitable food for fish. Theabundance of the carbon dioxide and nitrates is removed looooo
Text Appearing After Image:
Sampling Stations Yearly Averages of Organisms Fig. 35.—Diagram showing the abundance of microorganisms at the various sam-pling stations. by simple and higher plants which grow in such a quantityas to almost clog the stream and furnish protective habita-tions for the millions of tiny animals which nature is usingin the purification process. The accompanying diagram shows the effect upon thestream produced by introducing the sewage effluent, whichcame in between sampling stations No. 1 and No. 2. The othersampling stations indicated in the diagram are approximately WATER SUPPLY 239

Note About Images