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with more or less distinctness


Plate VII, B.
Photomicrograph of double twisted ribbon-like form of Spirophyllum Ferrugineum from city water, Madison, Wis., x640.
The dark masses are gelatinous ferric hydroxide. Unstained.
(cropped from border and page)

illustrating Edmund Cecil Harder. Iron-Depositing Bacteria and their Geologic Relations. USGS Professional Paper 113. (1919) *
Stanford copy, no date of digitization

More often, however, the two filaments forming such a thread can be traced with more or less distinctness.
p 25.

21 February 2014
tags: E. C. Harder; drawing; iron-bacteria; water