Water Relations of Plant Cells and Tissues

This review deals principally with papers which have been published dur­ ing the 5 years since the review by Kramer & Currier (69) appeared, but a few older papers have been cited to provide background material. No attempt was made to cite all papers published during this period, but an effort has been made to show the fields in which research has been active. Readers are referred to the reviews by Bogen in recent volumes of the Fortschritte der Botanik for additional literature and another viewpoint concerning cell water relations. In the review by Kramer and Currier considerable space was devoted to a discussion of the possiblity that the classical concepts of osmotic phenom­ ena are inadequate to explain fully cell water relations, and that some active or nonosmotic uptake of water may occur. The occurrence of nonos­ motic water uptake remains one of the most interesting problems in the field of water relations of cells and tissues, but although a number of inter­ esting and sometimes conflicting papers have appeared, it is still difficult to reach definite conclusions concerning its importance. A few years ago Steinbach (111) wrote that studies on permeability were being replaced by studies on accumulation and studies which stressed the dynamic characteristics of plant membranes. This probably is generally true, but several interesting papers on factors affecting the premeability of plant cell membranes have appeared in recent years. Even the old problem of terminology, which some of us hoped was satisfactorily settled by the dif­ fusion pressure deficit concept of Meyer (85), has been revived by several workers who prefer some other term. As Walter (121) wrote, Fast jeder Autor benutzt ein andere Bezeichnungsweise und mitunter widerspricht er sich selbst. While this reviewer does not recommend slavish adherence to custom he doubts if much has been contributed by recent attempts to revise our terminology.