CHAPTER I 



Introduction and Historical Background 



THE THEME of this book ccntres round the extraordinary advances 

 which have been made, during the past twenty-five years, in the 

 understanding of the molecular structure of the solid envelope which 

 surrounds every plant cell. It is fitting therefore, that we should consider 

 in the first place some of the multitudinous reasons for the current pre- 

 occupation with such a topic. Reasons in plenty are not far to seek — 

 they must in fact be obvious after a little thought even amongst those 

 of us unacquainted with plant science. From time immemorial man 

 has made use of plants, not only for food — for that would not help us 

 here since the bulk of the material we shall deal with is not digestible 

 in man's alimentary tract — but also in many other ways. From the 

 Garden of Eden downwards, use has been made of plant products to 

 cover human nakedness, a use widened enormously in scope by the dis- 

 covery of weaving since fibres of all kinds could then be manufactured 

 into sheets of cloth. Nowadays we are familiar with the weaving of flax 

 fibres into linen, with the weaving of hemp into ropes and jute into bags 

 and with the multitudinous uses of cotton fibres. All of these processes 

 exploit the very fibres which we shall be investigating here. More than 

 this, however, from times well before recorded history man has made 

 use of another plant product — timber — for the building of houses, for 

 furniture, and even for weapons of offence and defence. He has become 

 acquainted with the great strength and durability of such plant pro- 

 ducts and has made use of their peculiarities, of the lightness and resili- 

 ence of wood for instance. There can be no doubt but that the peculiar 

 combination of physical properties in these materials — and this short 

 list does not by any means cover all the queer mixture of properties — 

 is due in no small degree to the molecular structure of plant products 

 and, in particular, to the structure of the cellulose so ubiquitous in all 

 of them. As in many other branches of human endeavour, the uses of 

 these materials, and knowledge and exploitation of their peculiarities, 

 came long before any attempt could be made to explain them. Never- 

 theless explanation is surely needed, and all the more surely in this 

 modern age when so much of our economy depends on the faultless 



