The Strategy of the Genes

garded as a general introduction to the interesting new field of atomic medicine, it covers a vast amount of information on radioisotopes which are used in medical research, diagnosis, and therapy. The background of nuclear physics on each aspect of this new field of medicine is concisely explained. The medical use of high energy particle accelerators such as cyclotron, betatron, synchrotron, and linear accelerators are briefly described. The linear accelerator is considered as the machine which has real practical value in radiotherapy. In radiotherapy today in England there is considerable competition between linear accelerator and large telecurie units, such as Cobalt-60 or Cesium-137. Both these developments are important by-products of atomic energy development. The three dangerous biological effects of radiation to man are discussed in some detail: (1) immediate danger of tissue damage from individual high exposure, (2) long-term danger of chronic damage to tissue with possible induction of cancer, (3) remote but important danger of permanent genetic damage that may seriously affect future generations. The common levels of radiation exposure are listed in detail based on the data published in Great Britain. Some interesting estimated figures on radiation received by the whole population of Great Britain to reproductive organs in the first 30 years of life as a genetic hazard are abstracted as follows: Natural body radioactivity, 690 mr. The dose required to double human mutation rate is estimated to be 50,000 mr. The author also stresses the opinion that genetic damage by radiation is not yet fully understood and must be worked out as one of our most urgent problems. The material chosen is mainly from the British sources and is based on a comprehensive review of the literature of the subject. The illustrations .are excellent but no bibliography is appended. It is easy and pleasing to read and it should be recommended to medical students, nurses, and physicians who want to have a general and up-to-date view of this subject. "How does development produce entities which have Form, in the sense of integration or wholeness; how does evolution bring into being organisms which have Ends, in the sense of goal-seeking or directiveness?" An examination of these questions provides the unifying theme for this collection of essays which are Professor Waddington's most recent contribution to theoretical biology. Although portions of four of the five essays have appeared elsewhere in different form, they are essentially new and contain much …