A Symposium on Molecular Biology Edited by Raymond E. Zirkle (review)

ketonuria, galactosemia, several kinds ofclotting defect, acatalasemia, and most of the abnormal hemoglobins. In another generation I hope diat most people will be examined at puberty, told for what harmful recessive genes diey are heterozygous, and warned against marrying similar heterozygotes. If2 per cent ofall babies are homozygous for a harmful recessive, which I think is an exaggeration, 8 per cent ofmarriages will be contraindicated . Ifit is concluded diat X-rays—which are at present die main source ofgenetic damage—bomb tests, and peaceful uses ofatomic energy are increasing human mutation rates, the resulting scare may lead not only to increased medical research but to free and compulsory tests for heterozygosis. If so, die final effect of increased mutation on the human species may be favorable. I have criticized this book because, unlike a number which have been written on die same topic, it is worth criticizing. It can be recommended as a sane and balanced account ofthis difficult question. But I venture to hope that it will run to a second edition, and that, ifso, die above criticisms will be accepted or refuted. J. B. S. Haldane Indian Statistical Institute Calcutta, India A Symposium on Molecular Biology. Edited by Raymond E. Zirkle. Chicago: University ofChicago Press, 1959. Pp. viii-f-348. $7.50. What is molecular biology? The editor ofthis volume defines it as "a convenient term that designates die sum ofdie multifarious endeavors that aim at the explanation of life —phenomena in terms of the physical and chemical properties of molecules." It is a branch of biology in which advances have been unusually rapid during die decadejust passed, especially in die area of proteins and nucleic acid structure and function. Some appreciation ofthe tempo is gained from a footnote added in proofby Richard B. Roberts , the author of a chapter. He writes: "Knowledge of the particles has advanced so rapidly that reading diis paper is like visiting a museum." The pace ofdevelopments coupled widi the long lag between the symposium lectures in 1956-57 and their appearance in final printed form in mid-1959 means that die book has lost some part ofits value. In die intervening two years, institutes, laboratories, and special groups in molecular biology—some old, many new—were very busy. Perhaps in pleading for manuscripts from the most procrastinating ofhis contributors, the editor experienced delays even more frustrating than those suffered by the editors ofPerspectives in getting diis account from the reviewer. Nevertheless, the collection is an important indication ofdie state ofknowledge two to diree years ago. The structure ofdeoxyribonucleic acid proposed by Watson and Crick in 1953 was without doubt a most significant turning point in modern biology, for it so reasonably suggested how DNA—by then known to constitute die primary genetic material in some viruses and in some bacteria—might do the diings genes were known to do; namely, carry information, replicate, transfer information to other parts ofliving systems, and undergo mutational alteration. The Watson-Crick structure of DNA and some of its biological implications are given by Sinsheimer. 568 Book Reviews Perspectives in Biology and Medicine · Summer i960 Evidence suggesting how DNA might replicate according to die views of Watson and Crick is presented by three audiors: Sinsheimer, Rich, and Kornberg. More recent investigations greatly strengdien die case, although diere remain many unanswered questions. That chromosomal DNA of higher forms may likewise replicate according to the Watson-Crick scheme is indicated by the observations on plant chromosomes in which the DNA is labeled widi thymidine. The early observations are reviewed by Taylor. Again, subsequent studies amply confirm die findings reported in 1956-57. The classical studies of Hershey and Chase on bacterial viruses in which DNA and protein components were followed during and after die infection process through die use ofP32 or S3S labels were important in establishing the genetic significance of DNA in these systems. In the symposium volume, Kozloffconsiders the details of die remarkable process by which a bacterial virus "injects" its DNA core into a bacterial host cell during the process ofinfection. Luria gives details as to how the DNA ofa temperate bacterial virus establishes a nonlethal attachment to die host DNA during lysogenization. How is the...