The aim of this Treatise on Comparative Biochemistry is to provide a sound, critical, and provocative summary of present knowledge in the field. Although comparative biochemistry is the most recent approach to the study of biology, its domain is vast because it seeks to compare the physicochemical properties of every form of life. In this sense it includes ail of biochemistry, not only those aspects common to life in general, but also the unique physicochemical manifestations which are characteristic of each of the several million species of living organisms comprising the phylogenetic scale. Biological diversity is inherently as interesting to comparative biochemistry as biological unity. Furthermore, comparative biochemistry is concerned not only with contemporary life, but with life of all ages reaching back to origins; it views evolution in terms of molecular rather than morphological changes. In order to provide a systematic comparison of the biochemical phenomena of life throughout the phylogenetic scale, which has been our objective, the Treatise has been organized in the following manner: Volumes I and II are primarily concerned with the biological transformations of free energy. Volume I deals with the sources of biologically useful free energy, while Volume II describes how this free energy is utilized to support function. The structures of the principal classes of metabolites, their distributions, and the comparative enzymology of their biogenesis and metabolism are the subjects of Volumes III and IV. The comparative biochemistry of organized reactions Systems and the biological functions dependent upon these Systems are discussed in Volumes V and VI.

The aim of this Treatise on Comparative Biochemistry is to provide a sound, critical, and provocative summary of present knowledge in the field. Although comparative biochemistry is the most recent approach to the study of biology, its domain is vast because it seeks to compare the physicochemical properties of every form of life. In this sense it includes ail of biochemistry, not only those aspects common to life in general, but also the unique physicochemical manifestations which are characteristic of each of the several million species of living organisms comprising the phylogenetic scale. Biological diversity is inherently as interesting to comparative biochemistry as biological unity. Furthermore, comparative biochemistry is concerned not only with contemporary life, but with life of all ages reaching back to origins; it views evolution in terms of molecular rather than morphological changes. In order to provide a systematic comparison of the biochemical phenomena of life throughout the phylogenetic scale, which has been our objective, the Treatise has been organized in the following manner: Volumes I and II are primarily concerned with the biological transformations of free energy. Volume I deals with the sources of biologically useful free energy, while Volume II describes how this free energy is utilized to support function. The structures of the principal classes of metabolites, their distributions, and the comparative enzymology of their biogenesis and metabolism are the subjects of Volumes III and IV. The comparative biochemistry of organized reactions Systems and the biological functions dependent upon these Systems are discussed in Volumes V and VI.

The aim of this Treatise on Comparative Biochemistry is to provide a sound, critical, and provocative summary of present knowledge in the field. Although comparative biochemistry is the most recent approach to the study of biology, its domain is vast because it seeks to compare the physicochemical properties of every form of life. In this sense it includes ail of biochemistry, not only those aspects common to life in general, but also the unique physicochemical manifestations which are characteristic of each of the several million species of living organisms comprising the phylogenetic scale. Biological diversity is inherently as interesting to comparative biochemistry as biological unity. Furthermore, comparative biochemistry is concerned not only with contemporary life, but with life of all ages reaching back to origins; it views evolution in terms of molecular rather than morphological changes. In order to provide a systematic comparison of the biochemical phenomena of life throughout the phylogenetic scale, which has been our objective, the Treatise has been organized in the following manner: Volumes I and II are primarily concerned with the biological transformations of free energy. Volume I deals with the sources of biologically useful free energy, while Volume II describes how this free energy is utilized to support function. The structures of the principal classes of metabolites, their distributions, and the comparative enzymology of their biogenesis and metabolism are the subjects of Volumes III and IV. The comparative biochemistry of organized reactions Systems and the biological functions dependent upon these Systems are discussed in Volumes V and VI. The present volumes, III and IV, are devoted to the principal classes of constituents of cells and organisms, their distribution, and the comparative enzymology of their biogenesis and metabolism. The comparison of structure and distribution, on the one hand, and metabolism, on the other, require different types of specialized knowledge; we have asked two different authors, when necessary, to describe these different aspects of the composition of living organisms. In the main, organisms are made up of fatty acids and lipids, mono-and polysaccharides, amino acids and proteins, nucleotides and nucleic acids, and water. This is an aspect of biochemical unity to which, on earth at least, there appears to be no exception. It is logical to arrange the chapters in these volumes to emphasize this unity. There are also numbers of other structural classes of metabolic components which occur only in portions of the phylogenetic scale; these less usual components illustrate the diversity of life. A number of chapters in Volume IV are devoted to amino acids and proteins. Some of these chapters deal with special forms of adaptation of protein structure: keratin, sclerotized proteins, silk; or protein transformations during the coagulation of blood, or during amphibian metamorphosis. This group of chapters offers ample material for comparison in the field of the molecular biology of proteins. The editors, although they have preferred to delay publication of individual volumes rather than have chapters appear out of their organized context, have been confronted with serious difficulties arising from the necessity of translating manuscripts written in languages other than English, and of insuring the publication of texts already received without too long a delay. They have therefore decided not to postpone the printing of chapters already on hand. This somewhat upsets the original plan of organization which, nevertheless, continues to underlie the treatise as a whole. : ; As in the case of previous volumes, the publishers have provided us with prompt, competent, and reliable assistance. We wish again to express our gratitude to them.

The aim of this Treatise on Comparative Biochemistry is to provide a sound, critical, and provocative summary of present knowledge in the field. Although comparative biochemistry is the most recent approach to the study of biology, its domain is vast because it seeks to compare the physicochemical properties of every form of life. In this sense it includes ail of biochemistry, not only those aspects common to life in general, but also the unique physicochemical manifestations which are characteristic of each of the several million species of living organisms comprising the phylogenetic scale. Biological diversity is inherently as interesting to comparative biochemistry as biological unity. Furthermore, comparative biochemistry is concerned not only with contemporary life, but with life of all ages reaching back to origins; it views evolution in terms of molecular rather than morphological changes. In order to provide a systematic comparison of the biochemical phenomena of life throughout the phylogenetic scale, which has been our objective, the Treatise has been organized in the following manner: Volumes I and II are primarily concerned with the biological transformations of free energy. Volume I deals with the sources of biologically useful free energy, while Volume II describes how this free energy is utilized to support function. The structures of the principal classes of metabolites, their distributions, and the comparative enzymology of their biogenesis and metabolism are the subjects of Volumes III and IV. The comparative biochemistry of organized reactions Systems and the biological functions dependent upon these Systems are discussed in Volumes V and VI.