INTRODUCTION: WALLS AND CELLS 



When the cell theory and its origins are presented to the student 

 of botany or general biology, reference is almost invariably made 

 to the cellular structure of cork as described in Robert Hooke's 

 Micrographia. The existence of well-defined, limiting wall structures 

 has been of great importance in the development of the concepts 

 of biological organization. In the vascular plant body, a multitude 

 of varied patterns of cell and tissue organization underlie a compara- 

 tively simple array of organs. The identity of tissues and tissue 

 systems is based upon the cell types present and their arrangement, 

 and is referred in large measure to cell morphology. In many 

 cell types, form becomes fixed during maturation and differentiation 

 in the cell wall. Thus, the death of protoplasts often leaves behind 

 a permanent record of their size, form and arrangement. The 

 stability of the morphological system in vascular plants is illustrated 

 by the cellular and tissue structure which is often discernible in 

 fossils. 



Underlying the record of microstructure which the cell wall 

 provides is a vast supply of physicochemical information encompass- 

 ing the physical structure of polymer aggregates and polymer 

 chains, and the chemistry of polymers, monomers and other small 

 molecules. Therefore, a vital part of cellular economy is reflected 

 in the materials of the cell wall and the physicochemical proper- 

 ties of the protoplastic elements and membranes which regulated 

 their deposition. 



The cell wall is a highly functional entity which varies in 

 composition and architecture, internally in accordance with cell- 

 cell and cell-tissue interactions, and, externally in accordance 

 with environmental factors and stresses. 



The student of ontogeny, whether concerned with cellular 

 differentiation or morphogenesis in complex organisms, proceeds 

 with confidence that a relationship indeed exists between form 

 and function. The mechanisms of ontogenetic control constitute. 



