In many parts of vertebrate and invertebrate central nervous systems, groups of nerve or receptor cells can be found that are arranged and connected according to a precise, functionally defined pattern (Braitenberg, 1973; Santini, 1975; Strausfeld, 1976; Chan-Palay, 1977).
As editor of the two-part Volume V on photosynthesis in RUHLAND'S Encyclopedia, the forerunner of this series published in 1960, I have been approached by the editors of the present volume to provide a short preface.
The problems associated with the movement of water and solutes throughout the plant body have intrigued students of plants since Malpighi's conclusions in 1675 and 1679 that nutrient sap flows upward and downward in stems through vessels in both wood and bark.
One of the points clearly stressed in the beginning of this book is that the essential feature of any dynamic system is change and that, where there is change, there may also be growth and evolution.
Plant pathology embraces all aspects of biological and scientific activity which are concerned with understanding the complex phenomena of diseases in plants.
Animals are important components of any ecosystem and it is impossible to describe structure and funCtioning of the Fennoscandian tundra ecosystems without including this part of the system.
The public's serious concern about the uncertainties and dangers of the conse- quences of human activities on environmental quality demands policies to control the situation and to prevent its deterioration.
A book previously published within the framework of the Ecological Studies Series, entitled "e;Physical Aspects of Soil Water and Salts in Ecosystems"e; included awidespectrum of research papers devoted to new findings in the field of soil-plant-water relationships.
At the end of the last century and the beginning of this century, the prob- lems of immunity in lower vertebrates and the influence of environmental temperature attracted attention for the first time (ERNST, 1890; WIDAL and SICARD, 1897; METCHNIKOFF, 1901).
The papers collected in this book were given and discussed at the symposium on "e;Soil water physics and technology"e;, which was held in Rehovot, Israel, from August 19th-September 4th, 1971.
It is now generally accepted for a variety of reasons - morphological as well as physiologica- that the visual systems of arthropods provide a suitable model for the study of information proces- sing in neuronal networks.
Prominent progress in molecular biology was only made when it became possible to separate functionally distinct molecules by taking advantage of their biophysical properties.
Although this is basically a translation of the second German edition published in 1970, more recent experimental findings have, in several instances, been incorporated into the text.
This volume is dedicated to the memory of the late Professor WERNER BRAUN, one of the most devoted and active members of the Editorial Board of the Current Topics in Microbiology and Immunology, who passed away, after suffering a heart attack, in November 1972.
