FOREWORD 



AN architect must build upon the past. A study of the growth of 

 animal and plant organisms must start from a firm foundation 

 L in the mechanics of growth which finds its most eloquent expres- 

 sion in D'Arcy Thompson's Growth and Form. 



The symmetrical groupings which cells take in forming parts of 

 organisms, the time required for the attainment of such groups, the 

 numerous internal and external forces that give form to the individual 

 cells, the symmetry of form of the whole organism and between organ- 

 isms, all these and numerous other precisely measured parameters are 

 the foundations upon which the students of growth must build. 



The individual chapters of this book represent a number of sturdy 

 columns that are being erected upon these foundations. Examined 

 individually they make the reader want to take part in their construction. 

 Viewed as a whole they present a hope for a future understanding of 

 the phenomenon of growi:h. 



One of the fundamental processes in growth of plant or animal con- 

 sists in the manufacture of an ever-increasing amount and variety of 

 proteins. These proteins form the major structural components as well 

 as the organic catalysts of all living cells. Hence an analysis of the 

 mechanisms involved in the "Synthesis of Proteins" (Chapter I) is an 

 important part of a study of growth. 



"Morphology at the Molecular Level" (Chapter II) is rapidly becom- 

 ing an essential aspect of growth. It has already contributed greatly to 

 our understanding of the problem of the arrangement of protein and 

 other molecules within a cell, which determines the cells highly specific 

 form, symmetry and reactivity. 



At this point a question arises. What determines the mass and direc- 

 tion which these structural units and their accompanying water and 

 salts acquire in the growing organism? The problems raised by this 

 question differ somewhat in the growth of plant from that of animal 

 organisms. For this reason Chapters III and IV deal with "Plant Growth 

 Hormones" and "Vitamins and Growth Factors." 



Organisms, whether unicellular or multicellular, are composed of 

 cells which have arisen from preexisting cells. This is the fundamental 

 biological phenomenon of growth. Our present knowledge and future 

 prospects of understanding this phenomenon have been greatly acceler- 

 ated in recent years by studies on the "Kinetics of Growth of Micro- 

 organisms" (Chapter V). This leads naturally to a desire to know more 



