Relation of Aeration to the Activity of Proliferation-Promoting Factors from Injured Cells

Abstract

IN earlier tests of the proliferation-promoting activity of materials from injured cells (‘intercellular wound hormones’) in which yeast was used as the test organism¹, the test cultures were grown in rocker tubes with continuous shaking². This subjected them to appreciable aeration. In recent investigations of wound hormones, yeast was again employed as the test organism, but was cultured in stationary, cotton-plugged tubes suspended in a water bath. At intervals of several hours, the tubes were removed from the water bath, shaken, and the yeast population determined with a photo-electric densitometer. In these later experiments, all preparations failed to show appreciable activity, though they had been prepared strictly in accordance with previously used techniques¹.