Cryptococcosis

presses sporangiophore growth, and of the morphologic aspects of nuclear RNA. This latter paper, by a group from the University of Chicago, includes unusually clear electron photomicrographic evidence in support of the authors' claims. The structure of plant cilia and their similarity to those of animals (Manton) and a study of nucleo-cytoplasmic interactions and morphogenesis in Stentor (Tartar) are the contributions concluding this section. A greater degree of unity can be detected in the second part, which is comprised of papers dealing with intercellular events. The reciprocal effects of humoral, neural, and other agents in neurogenesis are discussed by Hamburger, while Niu contributes a description of his technique of embryonic induction via diffusible substances. The Lederbergs deal with problems of transduction and consider some of the broader implications of bacterial genetics. The interactions of slime-mold cells in development (the Sussmans), an analysis of plant shoot growth (Wetmore), the induction of heterologous tolerance (Billingham), and a description of the differentiation of the myelin sheath (Geren) rounds out part two. Altogether, the collection of Growth Symposium volumes represents an impressive indication of the progress being made in this difficult field.