Use of Frozen Vacuum-Dried Material in Auxin and Other Chemical Analyses of Plant Organs: Its Extraction with Dry Ether

A method is described for drying frozen plant material in vacuum with a minimum of chemical alteration, which is highly desirable for auxin and other chemical analyses. Material so prepared is auxinic and gives greater yields of auxins than fresh material. 2. Ether dried over sodium does not extract auxins from the material, nor does absolute alcohol. If a little water is added to such ether or to a dry ether-alcohol mixture, an active extract is obtained. Water extracts of such material alone are highly active. The material is lyophile, speedily taking up water from the solvent. 3. The auxin liberated by water from dry material is soluble in dry ether. Water is necessary for the presence of active auxin in plant tissues. Freezing or drying, or both, apparently leads to destruction of active auxin or to its fixation in a nonremovable form. 4. Pretreatment of dry material with dry ether removes ether-soluble substances and yields a partially fat-free and ether-soluble pigment-free sample for auxin extraction. This should facilitate isolation and identification of auxins. 5. These findings so far apply to all materials tested: nodules of red kidney bean, hypocotyl of tomato, and hypocotyledonary gall of tomato incited by Phytomonas tumefaciens.