U. Lüttge – författare

This book is addressed to all biologists seeking a review of the various transport processes of minerals and organic substances in plants from the level of cell organelles to the longer-distance movements in the largest trees. It is directed toward students having had some elementary physiol­ ogy, but the attempt has been made to provide information of interest on the frontiers of current research. Doing this comprehensively, we wished to consider all of the points of view that appeared to be important; on the other hand, space and time were limited. Therefore, the presentation had to strike an intermediate ground between the style of a textbook giving of selected problems and a comprehensive ref­ representative treatments erence book covering all ramifications. The reader will notice that the pendulum will swing more toward one and then to the other. We did not want to avoid, and we felt it was not appropriate to neglect completely our own special research interests, which led to some emphasis on certain SUbjects. The immediate origin ofthe book is the Heidelberger Taschenbuch 125 (HTB 125) Stojjtransport der Pflanzen by U. L. (1973), which in turn was preceded by an earlier work, Aktiver Transport: Kurzstreckentransport bei Pflanzen Protoplasmatologia vol. VIII17 b by U. L. (1969). At the Li­ verpool Workshop on Ion Transport in 1972 organized by W. Peter An­ derson, and while in a jovial and expansive mood, the authors agreed to produce an English version.

In biological literature, several definitions of quantitative autoradio­ graphy are given. The term is defined as either the determination and com­ parison of the density of silver grains above various structures or under varying conditions, or the determination of absolute quantities of radio­ activity. In both these cases, photometric measurement serves for more rapid and more exact evaluation of grain densities than would be possible by visual counting of the grains. The equipment generally used for the photometric measurement of silver grains consists of a microscope, a photocell, an electronic amplifier system and a display unit. Grains can be made accessible to photometric evaluation by various kinds of microscopic illumination: 1. Substage bright-field illumination. 2. Substage dark-field illumination. 3. Incident dark-field illumination. 4. Vertical bright-field illumination. With all these types of illumination, the relationship between the luminous flux I absorbed by the film, scattered into the objective and reflected or diffracted, and the flux 10 which is not affected by the film is used as a measure of grain density. Since these are differential measurements, the light beam I transmitted by the film is in itself a measure of grain density if the luminous flux 10 incident on the grains is kept constant. This approach has been used in a large number of measuring setups.

With one volume each year, this series keeps scientists and advanced students informed of the latest developments and results in all areas of the plant sciences.The present volume includes reviews on genetics, cell biology, physiology, comparative morphology, systematics, ecology and vegetation science

With one volume each year, this series keeps scientists and advanced students informed of the latest developments and results in all areas of the plant sciences.The present volume includes reviews on genetics, cell biology, physiology, comparative morphology, systematics, ecology and vegetation science

With one volume each year, this series keeps scientists and advanced students informed of the latest developments and results in all areas of the plant sciences.The present volume includes reviews on genetics, cell biology, physiology, comparative morphology, systematics, ecology and vegetation science.

As plant physiology increased steadily in the latter half of the 19th century, problems of absorption and transport of water and of mineral nutrients and problems of the passage of metabolites from one cell to another were investigated, especially in Germany. JUSTUS VON LIEBIG, who was born in Darmstadt in 1803, founded agricultural chemistry and developed the techniques of mineral nutrition in agricul­ ture during the 70 years of his life. The discovery of plasmolysis by NAGEL! (1851), the investigation of permeability problems of artificial membranes by TRAUBE (1867) and the classical work on osmosis by PFEFFER (1877) laid the foundations for our understanding of soluble substances and osmosis in cell growth and cell mechanisms. Since living membranes were responsible for controlling both water movement and the substances in solution, "permeability" became a major topic for investigation and speculation. The problems then discussed under that heading included passive permeation by diffusion, Donnan equilibrium adjustments, active transport processes and antagonism between ions. In that era, when organelle isolation by differential centrifugation was unknown and the electron microscope had not been invented, the number of cell membranes, their thickness and their composition, were matters for conjecture. The nature of cell surface membranes was deduced with remarkable accuracy from the reactions of cells to substances in solution. In 1895, OVERTON, in U. S. A. , published the hypothesis that membranes were probably lipid in nature because of the greater penetration by substances with higher fat solubility.

In the first part (Part A) of this volume on transport, there was an emphasis on the processes occurring at the membranes bounding the cells. It was convenient to distinguish active and passive processes of transport across the membranes, and to recognize that certain transport processes may be regulated by internal factors in the cells such as cytoplasmic pH, concentrations of ions, of malate or of sugar in the vacuoles, or the hydrostatic pressure. Cells in tissues and organs show the same kinds of properties as individual cells, but in addition there can be cell to cell transport related to the organization of the tissue. Firstly cells within a tissue are separated from the external solutions by a diffusion path comprising parts of the cell walls and intercellular spaces; more generally this extra-cytoplasmic part of the tissue has been called the apoplasm. A similar term is "free space". Secondly, the anatomy of cells in tissues seems to allow some facilitated, local transport between cells in a symplasm. Entry into the symplast and subsequent transport in a symplasmic continuum seems to be privileged, in that ions may not have to mix with the bulk of the cytoplasm and can pass from cell to cell in particular cytoplasmic structures, plasmodesmata. In Chara plants, this kind of transport is found operating across the multi-cellular nodes as the main means of transport between the long internodal cells.

With one volume each year, this review series keeps scientists and advanced students informed of the latest developments and results in all areas of the plant sciences. Starting with this volume, the sections of PROGRESS IN BOTANY have been restructured. The new sections - Genetics - Cell Biology and Physiology - Systematics and Comparative Morphology - Ecology and Vegetation Science - correspond to the subdivision of the field of botany generally used by the scientific community.