S. Rodionov and G. Frank. Issues of Photobiology and Light Measurement. GTTI, L.–M., 1934, 86 pp., price 2 rubles.

In keeping with its rather ungainly title, the booklet may be divided into two parts: biological and physical. The biological part is a brief survey of the basic facts in the field of Gurwitsch’s mitogenetic rays. We think that every physicist will find it interesting to become acquainted with one of the most remarkable discoveries in biology in recent times. The biological questions are presented in a form accessible to any nonspecialist. At the same time, much space is devoted to the specificity of this type of radiation from the physical point of view, which increases the interest of the physicist in the book.

The physical part of the book gives a survey of various methods for measuring radiation of weak intensity. Here, in addition to a review of literary data,

much information is given on the methodology used by the authors themselves. Of greatest interest are the application of objective nephelometric methods to the counting of bacteria and the detailed description of the work involved in improving photoelectron counters. It must be said, however, that from all the material presented by the authors one is nevertheless led to the conclusion that the measurement of weak intensities is still in a very unsatisfactory state. Extremely valuable, however, is the authors’ consistent introduction of objective methods—imperfect though they may be—into the practice of biological measurements; this gives the book under review its undoubted merit. A whole brief survey of light filters and ultraviolet sources is also touched upon (cellulose-acetate film, hydrogen tube, etc.).

The arrangement of the book as a whole gives an impression of incompleteness. The book should be regarded simply as “first-hand” information on the progress of an extremely interesting undertaking, which is still in its initial stage; much has been done, but still more lies ahead.

V. Fabrikant