Morphometry of the Human Lung

results of many experiments with much discussion as to their meaning, the questions were of the "I should like to ask Dr. X why he said so and so" variety. In contrast, the questions following the sessions in which the short communications predominated were of the "I should like to present the results of a recent experiment performed in my laboratory" variety. Most interesting among those articles in which the author's recent work is presented is Bullough's paper, in which he discussed his recent experiments with a substance he has isolated from epidermis and which in complex with adrenalin seems to inhibit mitosis in mouse epidermis. He calls this substance "chalone". Also notable was the contribution of Feldman, et al., in which their experiments were described demonstrating the failure of thymectomized mice subjected to total body X-irradiation to reject tumor transplants unless they received regrafts of intact thymuses from either newborn mice or one month old donors. Throughout this volume the reader finds lip service being paid to "Jacob and Monod" (no less than 20 references), "induction and repression," "operon", "derepression", etc. The last section of Prof. Kaplan's closing paper is entitled, "Can we propose testable molecular mechanisms for the neoplastic transformation?" Instead of answering this question directly, Prof. Kaplan proceeds to present an elaborate Jacob and Monod-type model consisting of a "Differentiation Operon" and a "Replication Operon," each induced and repressed by a complex system of interacting inducers, effectors, and repressors. No mention is made of an essentially identical model invoked by Bullough earlier in the conference in his excellent paper on chalone. Although this sort of Model-building is great sport, one would have hoped that Prof. Kaplan and others at this conference would have instead, devoted some thought to the problem of the experimental demonstration of Jacob and Monod's model (documented by them for B-galactosidase in E. coli) in higher organisms. There are, however, no more than numerous invocations of the operon model with no consideration of the monumental difficulties involved in applying this model to mammalian tissues and demonstrating it experimentally. It is difficult at this time to see any useful purpose in publishing such mental gymnastics. This collection of papers probably contains little that is new or useful to the experienced investigator. The review papers should prove of value to the student interested in molecular biology and carcinogenesis. There is a danger, however, that those unfamiliar …