Reviews

Comparative Animal Physiology. By C. L add P rosser et al. Organisme et Sexualité. By M. C aullery . Embryos and Ancestors. By G. R. de B eer . The Association of Ants with Aphids and Coccids. By G. E. J. N ixon . Soil and Fresh‐Water Nematodes. By T. G oodey Die Überträger pflanzlicher Viruskrankheiten (The vectors of plant viruses). By K urt H einze . Leaf Curl Disease of Cotton. By S. A. J. T arr . Introduction to Mycology. By J. A. M ac D onald . Pesticide Handbook 1951. Edited by D. E. H. F rear . Pflanzliche Infektionslehre. By E rnst G äumann . A Dictionary of Biology. By M. A bercrombie , C. J. H ickman and M. L. J ohnson . Soviet Genetics. By A. G. M orton . Gall Midges of Economic Importance. Vol. v. Gall Midges of Trees. By H. F. B arnes . Four Thousand Million Mouths. Scientific Humanism and the Shadow of World Hunger. Edited by F. L e G ros C lark and N. W. P irie .