... twenty minutes centrifugating at a speed of about 2400 revolutions per minute the yeasts in the solution have all been packed into the tip and the volume can then be read accurately to thousandths of a cubic centimeter (with the aid of a scale and magnifier). With a control tube containing 9 cc. of the sterile media and 1 cc. of distilled water in place of the 1 cc. of extract a comparison can be obtained which is an accurate measure of the stimulatory effect of the extract. If this stimulus is due purely to vitamine it is ... — The Vitamine Manual • Walter H. Eddy
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