Plant Growth Substances

Abstract

FOLLOWING a project first put forward in 1925, the Committee on Intellectual Cooperation of the League of Nations and the International Council of Scientific Unions have agreed to collaborate in the calling of occasional conferences on well-defined fields. The first of these, on the plant growth substances, or phytohormones, was held in Paris on October 1-2, 1937, under the joint auspices of the C.I.C. and the International Union of Biological Societies. The report of the conference,* which has just been issued, contains eight contributed papers and discussion. Prof. Kogl (Utrecht) describes the determination of the chemical nature of auxins a and b and the isolation of biotin. Dr. Niels Nielsen (Copenhagen) discusses the substances promoting growth in the fungi, and the difficulties introduced by the varying abilities of organisms to synthesize different members of the group of active substances. The evidence associating the formation and action of auxins with oxidative metabolism is reviewed by Prof. Koningsberger (Utrecht), the phenomenon of bud inhibition and other correlations by Prof. Dostal (Brno) and the relation between the phytohormones and plant tropisms by the chairman, Prof. Boysen Jensen (Copenhagen). Prof. G. S. Avery (New London, U.S.A.) makes a plea for the consideration of the auxins as protoplasm irritants or 'evocators'. Prof. Bouillenne (Liege) discusses the action of auxins on cell division and root formation, and expresses the rather surprising opinion that although promotion of cambial division and inhibition of lateral bud development occur on applying pure auxins, at concentrations within the physiological range, to a variety of plants, nevertheless "under natural conditions"the auxins do not have these effects. Finally, Mile. Zollikofer (Zurich) reviews the rather unsatisfactory state of the work on the effect of animal hormones on plant growth. It seems unfortunate that Prof. NSmee, who (according to the preface) proposed the conference, and who has long been active in the closely related field of regeneration, should not have been present.