The Orientation of Animals

SINCE Jacques Loeb formulated his tropism theory some fifty years ago, a vast amount of work has been done on the orientation of the lower animals in relation to light and other environmental stimuli. This is well summarized and discussed in the present volume by Drs. Fraenkel and Gunn. In its original form the theory of Loeb cannot be upheld; a classification of these elementary reactions proposed by Kühn in 1919 has to a large extent taken its place in the minds of those who approach animal behaviour from the physiological point of view. It is to Fraenkel that we owe the first full exposition of Kühn's views published in Great Britain (1931), and to Gunn the revised and modified classification here presented in the first part of the book. He distinguishes between kineses or undirected reactions, taxes or directed reactions, and transverse orientations (to light and gravity). Kineses are subdivided into ortho-kineses and klino-kineses, and taxes into klino-taxes, tropo-taxes, and telo-taxes. In the second part of the book the available data about these reactions are considered under the headings of the different kinds of external factors “which control them”—temperature reactions, gravity reactions, reactions to chemical stimuli and so on. Many of these chapters are exceedingly valuable to the serious student by reason of the wealth of references and the careful exposition of the most modern work on the subject. The book is very well indexed and there is an extensive bibliography.The Orientation of AnimalsKineses, Taxes and Compass Reactions. By Gottfried S. Fraenkel and Donald L. Gunn. (Monographs on Animal Biology.) Pp. viii + 352 + 10 plates. (Oxford: Clarendon Press; London: Oxford University Press, 1940.) 21s. net.