2 THE MOLECULAR ARCHITECTURE OF PLANT CELL WALLS 



processing of huge quantities. Without such explanation it becomes 

 impossible to control adequately the varied, and nowadays very com- 

 plicated, treatments which the raw material receives; and, in particular, 

 if anything goes wrong it is not otherwise easy to put it right again 

 without serious loss. Finally, it is impossible to devise new uses, or to 

 explore the old ones thoroughly, without a good deal of ordered and 

 accurate information concerning the most intimate details of the 

 materials concerned. Realization of these matters has led to the 

 founding throughout the world, in the growing areas as well as in the 

 processing, of scientific laboratories devoted to the problems involved. 

 This is by no means all, however, and this fails by a long way to 

 exhaust the reasons for study of this particular field; it is certainly not 

 the major reason for writing this book nor does it express in any large 

 measure the fascination of the subject for the author, for any of those 

 whose help it will be an honour to acknowledge, or for any of the long 

 sequence of scholars — for scholars they are even though also scientists! 

 — whose names will grace these pages and in whose footsteps the author 

 and his associates now humbly tread. Apart altogether from its im- 

 mense impact on the welfare of human beings, a knowledge of how 

 things grow, whether animal or plant, can hardly fail to be of interest to 

 all of us, and this means in the long run a knowledge of the reactions 

 of the protoplasm — the stuff of which all living things are composed 

 and by whose activity they develop. There are naturally many avenues 

 along which such a study can properly be approached, and are being 

 approached; but none of them can be more fundamental than the 

 approach through structure. Until the structure of the living material 

 is fully understood there can be no real appreciation of the course of 

 growth. From this point of view, and since in very general terms proto- 

 plasm is very much the same in whatever body it is organized, it is 

 immaterial whether we concern ourselves with plants or with animals, 

 and in some respects plants offer more favourable material for explora- 

 tory purposes. Just as animal bodies produce structural proteins such 

 as hair, whose study at the hands largely of Professor W. T. Astbury 

 has led to such sweeping developments in the field of protein physics 

 and chemistry, so in plants we find structural polysaccharides. These 

 are, chemically speaking, a far cry from the proteins, and therefore 

 several steps removed from the molecular species which undoubtedly 

 confer upon protoplasm its particular and still cryptic features. Never- 

 theless their production in intimate contact with the protoplasm makes 

 it very probable that, as an end product in carbohydrate metabolism, 

 they have a good deal to tell us concerning protoplasmic structure and 



