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that is, by evaporating the ‘activator’, such as TI or Pb, on to the surface of the halide as a thin layer. The semi-conducting properties of layers of dyes and similar substances were also investigated in detail. The signs of the photo-current carriers were determined, and a close relationship found between the threshold quantum and the thermal activation energy of semi-conduction, which was attributed to the influence of crystal defects. He has lately carried out extensive work on photo-ionization and photo-dissociation of aromatic molecules by vacuum U.V. radiation, both for vapours and solids. Many of his results in this field have implications for photo#-biology ; they may be found summarised in his book, Photochemistry of Dyes and related Organic Compownds (Moscow, 1947), in articles in Vol. 2 of Advances in Photochemistry (Inter- science 1964), and in Recent Progress in Photobiology (Blackwells, to appear in 1965). Of special importance for photobiology is his work on energy transfer between triplet levels of molecules, demonstrated by sensi- tized phosphorescence. Both inter- and intra-molecular triplet transfers were shown to occur in simple systems, and are now recognised as of prime importance in photosynthetic processes.

It is characteristic of Professor Terenin’s published researches that few have ended in inconclusive results. He possesses the supreme faculty of being able to ask the right question in the design of his experiments, and has been constantly rewarded by significant conclusions. He stands today second to none in the field of the basic processes of photochemistry.

E. J. BOWEN

INTER NATIONAL PHOTOBIOLOGY CONGRESS, OXFORD, 1964

Tm IVth International Congress of Photobiology, held at Oxford University, Oxford, England, on July 27-30, 1964, followed the paittem of some past congresses in making use of rapporteurs to summarize groups of related papers while holding sectional meetings which permitted individual presentation of reports not readily fitted into a homogeneous framework. Translation service of all reports into English, French, German and Russian was available.

The seven rapporteur sessions reflected the broad but basic interests grouped under the banner of photobiology: basic photo-chemistry in relation to photobiology; photochemistry of nucleic acids and its biological implications; visual processes in man and animals; molecular and fine structure of receptors; photoenvironment; energy convenion and the photosynthetic unit; and micro-irradiation of cells. Each rapporteur session began with an introductory lecture by an outstanding authority in the field, followed by the rapporteur’s summary of ,a group of papers, and terminated by a discussion during which the authors of the summarized papers could be questioned by the audience for further details of technique, data or interpretation. The success of each session was a function of the skill of the individual rapporteur; by and large, the seventy-one papers were treated well and ably.

Sixteen sectional meetings, with a maximum of three taking place concurrently, provided an opportunity for the presentation of 155 individual reports. In subject matter, thBe complemented and extended the areas covered by the rapporteur sessions. Concurrent sessions led to some overlap in subject matter, but the degree of inconvenience was minimal. In addition, two symposia were held. The first dealt with light and melanin pigmentation of the skin, the other with the roles of photochemistry and photobiology in space research.

The Congress was attended by nearly 500 scientists from twenty different nations. The informality of the meetings, the excellent arrangements, the gracious hospitality of British town and gown, and the oppor- tunity for active and fruitful discussion combined to make the meetings a success. The British Organizing Committee, under the chairmanship of Professor Bowen, made the meeting a memorable one.

C. SWANSON

NOTICE IT is regretted that the publication of Photochemistry and Photobiology 3, 4 (Conference on molecular mechanisms in Photobiology, Wakulla Springs, Florida, February 16-21, 1964) has been delayed, and will appear early 1965.