1. Secondary Metabolism and Differentiation In addition to the primary metabolic reactions, which are similar in all living beings (formation and breakdown of nucleic acids and proteins as well as of their precursors, of most carbohy drates, of some carboxylic acids, etc. ), a vast number of metab olic pathways lead to the formation of compounds peculiar to a few species or even to a single chemical race only. These reac tions, in accord with CZAPEK (1921) and PAECH (1950), are summed up under the term "secondary metabolism," and their products are called "secondary metabolites. " The wide variety of secondary products formed in nature includes such well-known groups as alkaloids, antibiotics, cardiac glyco sides, tannins, saponins, volatile oils, and others. A consider able number of them are of economic importance in therapeutics or technology. Although secondary products are produced by micro organisms, higher plants, and animals (cf. LUCKNER, 1972), most of the substances are found in the plant kingdom. The lack of mechanisms for true excretion in higher plants may result in this unequal distribution, the "waste products" of metabolism in plants instead being accumulated in the vacuoles, the cell walls, or in special excretory cells or spaces of the organism ("metabolic excretion," cf. FREY-WYSSLING, 1935, 1970; MOTHES, 1966a, b, 1972; LUCKNER et al., 1976. Many secondary substances have, however, a direct biologic func tion. They can be regulatory effectors, e. g."

Die Geschichte der Naturwissenschaften und der Technik ist in den letzten Jahrzehnten um wichtige neue Aspekte und Interpretationen bereichert worden. Diese Ergebnisse waren aber bis jetzt nur in Spezialistenkreisen bekannt und verbreitet. Mit dieser Reihe werden nun die vielen Einzelergebnisse zusammengefasst und einem breiten Publikum prasentiert. International anerkannte Wissenschafts-Historiker schreiben uber ihr Spezialgebiet, ohne nur die Fakten aufzuhaufen, sondern unter Betonung der gemeinsamen Themen uber lange Zeitraume und uber alle Grenzen hinweg."

This is an EXACT reproduction of a book published before 1923. This IS NOT an OCR'd book with strange characters, introduced typographical errors, and jumbled words. This book may have occasional imperfections such as missing or blurred pages, poor pictures, errant marks, etc. that were either part of the original artifact, or were introduced by the scanning process. We believe this work is culturally important, and despite the imperfections, have elected to bring it back into print as part of our continuing commitment to the preservation of printed works worldwide. We appreciate your understanding of the imperfections in the preservation process, and hope you enjoy this valuable book.

Thousands of Jews and "Aryan" Germans opposed to Hitler led illegal lives under the Nazi terror and survived the relentless hunt of the Gestapo, the concentration camps, and the bombing. They survived in various ways; some as ordinary citizens taking part in the work-day life, others with fake passports, hidden in cellars, living precariously in all the dark corners of a vigilantly policed country. In fourteen autobiographical accounts, author Eric Boehm offers a cross-section of these heroic personalities. "We Survived" is itself an historical document, giving a window back into this epoch period during World War II.Now reappearing in print over fifty years after its original publication, "We Survived" remains as relevant and necessary as ever before - an honest testimony to the strength of the human spirit when it triumphs over adversity.