Preface 



An explanation of the sub-title of this work may not be out-of-place 

 since it will explain at the same time the treatment of the main theme. 

 The term molecular biology has gained currency recently; its use implies 

 an attitude towards biology, an acceptance of the belief that biological 

 phenomena can be related to the interaction of the molecules found in 

 biological systems. In practice it means that the primary emphasis is 

 placed on the determination of molecular structure by any of the means 

 available. 



In its pretensions molecular biology is a generalized science; it aims to 

 provide a common, integrating background to such special sciences as, 

 for example, biochemistry, histology and physiology, by rendering them 

 alike explicable in terms of molecular interaction. The name but not the 

 subject matter is new. In the pre-war period such writers as K. H. Meyer 

 and H. Mark, W. T. Astbury, J. D. Bernal, W. J. Schmidt, F. O. Schmitt 

 and A. Frey-Wyssling, to mention only a few, had the objective well in 

 mind. What is new, however, is the tempo of achievement in the post- 

 war years; detailed structures of key biological macromolecules have 

 been obtained and a complete coverage of cellular contents of all dimensions 

 is possible now by means of microscopy. These achievements have lifted 

 the dream of relating structure and function out of speculation to become 

 a problem capable of experimental investigation. 



That it is still largely a project one realises quickly enough in setting out 

 to give an account of even a simple, relatively uniform group of tissues 

 such as the epidermis and its appendages. Thus, while this book attempts 

 to pose the problems of keratinization consistently in molecular terms 

 and to avoid concepts not stateable in such terms, it rather quickly 

 degenerates into an outline of unsolved problems. Keratinization will 

 be regarded as a development of certain primitive cellular traits adapted 

 to serve the end of providing a protective coating to a multicellular 

 organism. The traits emphasised are intercellular adhesion and the 

 proliferation and stabilization of cytoplasmic protein filaments. We shall 

 be concerned for the most part with the structure and synthesis of these 

 filaments, with the structure of cell membranes and the nature of inter- 

 cellular adhesion. 



I am grateful to Professor A. Haddow, f.r.s., Director of the Chester 

 Beatty Research Institute, where I have found the opportunity to 



