I Five years ago, at this Svmposium. E. L. Tatum I , u , L and J. Lederberg first reported some preliminary experiments on genetic recombination in Escherichia coli K-12 (1946). This report will review subsequent developments in this research, with special emphasis on the application of recombination analysis in bacteria to problems of general genetic interest. The standard textbooks of bacteri...

The blood was obtained from the finger and collected in small test tubes, using as an anticoagulant one drop of 3.8 percent dihydnc sodium citrate for every ten drops of blood. Two percent suspensions of the red cell sediments in saline solution were prepared, and the A , B groups and M , N types were determined. The tests for these agglutinogens were carried out on Boerner well slides, one dro...

In experimental organisms such as fruit flies and mice, increased frequencies in germ cell mutations have been detected following exposure to ionizing radiation. In contrast, there has been no clear evidence for radiation-induced germ cell mutations in humans that lead to birth defects, chromosome aberrations, Mendelian disorders, etc. This situation exists partly because no sensitive and pract...

on " The Evolution of the American Girl" ! We have read the book from beginning to end with astonishment, almost with awe. It is brimful of noble sentiments and elevating advice; it bristles with figures of speech, and is not devoid of distinct efforts at logical reasoning. But somehow we cannot help smiling as we read; for bathos jumbles pathos, the ridiculous ousts the sublime, the culture of...

Next he discusses biometry as founded in Britain by Galton and as advanced by Karl Pearson, and he attributes great credit to the work of these men. To Semon, the author of Mnemism, Dr. Hart refers without immoderate criticism, but he suggests that the engram theory is as hypothetical as any of the suppositions of scholastic philosophy. He next proceeds to describe what is meant by mutation, bu...

In this paper, we study the behaviour of the generalized power domination number of a graph by small changes on the graph, namely edge and vertex deletion and edge contraction. We prove optimal bounds for γP,k(G − e), γP,k(G/e) and for γP,k(G − v) in terms of γP,k(G), and give examples for which these bounds are tight. We characterize all graphs for which γP,k(G− e) = γP,k(G) + 1 for any edge e...

In this review, I give a brief summary of galaxy evolution processes in hierarchical cosmologies and of their relative importance at different masses, times, and environments. I remind the reader of the processes that are commonly included in modern semi-analytic models of galaxy formation, and I comment on recent results and open issues.

tent of twin resemblance by means of a number of mental and physical measurements. Since that time, a growing realization of the importance of studying twin resemblance to determine the relative influence of heredity and environment, has led a large number of investigators to turn their attention to this problem. Rexroad,3 in a recent article, has assembled the results of fifty-seven studies of...