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Fred, Edwin Broun; Baldwin, Ira Lawrence; McCoy, Elizabeth / Root nodule bacteria and leguminous plants
(1932)

Appendix,   pp. 257-269


Page 257


                                  APPENDIX
                DIRECTIONS FOR THE USE OF ARTIFICIAL CULTURES
     The manufacturers of artificial cultures usually send out with their
products
specific directions for inoculation. It will be well to cite here two typical
sets
of instructions, illustrating the milk and water methods of inoculation.
The
Rothamsted method for alfalfa, as stated by Russell, 1926, is as follows:
      1.-Keep the cultures in the dark until used.
      2. In the cultures the bacteria appear as a whitish slime on the inclined
         surface of the jelly medium.
      3. Transfer the contents of the tube into fresh skim milk, using about
Y4
         pint of milk and 1 gram per quart of calcium phosphate (CaH, (PO4),.
         2H20) per tube of culture.'     Turn out the contents of the tubes,
         using a clean stick, and thoroughly mix the bacterial slime with
the milk,
         picking out the lumps of jelly medium. Rinse the tubes out into
the
         milk.
      4. The seed should be piled on a clean surface and the milk poured
on to
          it and well mixed with the seed so that every seed is moistened
with milk.
          It usually takes about a quart of milk to every 24 lb. of seed.
If there
          is not enough milk, add a little clean water till all the seed
is moistened.
      5. The seed should be sown as soon as possible after inoculation. If
the
          seeds are too wet and stick together, mix them with a little dry
earth or
          sand till they are dry enough to drill.
      6. The seed should be drilled and not broadcast, as it must not rest
on the
          surface of the ground, because light kills the bacteria. For this
reason,
          also, the inoculated seed must not be exposed to the sun before
drilling.
     A slight modification of this method appeared in the paper by Thornton,
 1929a. The principal changes consist in the use of 1 tube of culture to
7 lbs.
 of seed and of Y4 pint of skim-milk containing 0.1 per cent of calcium di-acid
 phosphate to 7 lbs. of seeds. Skim-milk instead of whole milk is recommended
 with the remark that it "greatly shortens the time of drying."
      The directions for use of cultures as recommended by the University
of Wis-
 consin will serve as an illustration of the water method of inoculation.
The cul-
 tures are supplied in large- and small-sized bottles. The quantity of seed
for which
 one bottle is intended is specified on the label; it varies according to
the variety of
    'The required amount of calcium phosphate is sent out with the cultures.
This should be
 dissolved in the milk before the bacteria are added.
                                         257


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