Practical bacteriology for chemical students / by David Ellis.

  • Ellis, David, 1874-1937.
Date:
1923
Catalogue details

Licence: In copyright

Credit: Practical bacteriology for chemical students / by David Ellis. Source: Wellcome Collection.

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    r* the regulation of gas is effected by a small disc like capsule containing a liquid which boils at a certain fixed temperature. The gas-valve shown in Fig. 4 illustrates this type. See also Fig. 5- Fig. 5.-—Regulator of Hearson’s. Incubator. A Inlet for gas. C Outlet for burner. B to D the lever. G Pivot on which lever works. P Millhead Screw. S Screw needle. Choice of temperature for cultivation of organisms. Every organism has its minimum, optimum and maximum temperatures of growth. It should therefore be the aim of the student to grow a microorganism as near to its optimum temperature as possible. It must be borne in mind, however, that most organisms will grow at the ordinary temperatures of the room, only growth will not in the majority of cases be quite as pronounced as when the organisms are placed inside an Incubator set at a slightly higher temperature. The following temperature- , ... Fig. 6.—Apparatus for list will Serve as rough guide. keeping sterilised water. Water conies out from the Pathogenic bacteria 370 C. (The temp, of the body.) Non-pathogenic bacteria 28° C.—320 C. Yeasts 25 0 C. — 28°. Moulds 30 0 C. — 40 0 C. tube B, and the air which displaces the escaping water comes in through the tube inside A. Both ends (A and B) must there- fore be protected. End B is placed in a tube con- taining alcohol. End A is covered by a tube con- taining usually cottonwool.