CONSTITUTION AND ARCHITECTURE IN THE CELL WALL 11 



II. The Results of Analysis 



An accurate accounting of cell wall components depends for its 

 construction upon the thoughtful application of the chemical 

 and physical methods of analysis which have been discussed. 

 Although there are, undoubtedly, many improvements yet to be 

 made in the particulars of cell wall analysis, the greatest need 

 lies in the interpretation of data and the development of an integral 

 picture of the cell wall as an organized system. 



Before attempting to make a synthesis of the various kinds 

 of analytical data at our disposal, we must of course, examine 

 more closely the information which these data yield about the 

 constitution and organization of the polymers and other molecules 

 which provide the elements of cell wall structure. 



Fractionation of the Whole Cell Wall 



Before examining a separation scheme, we may note by way 

 of review, the salient solubility properties of individual wall constit- 

 uents (Table 1). Cellulose and the cuticular substances are notably 

 more resistant to an array of solvents than are the other compo- 

 nents, lignin included. Lignin, the cuticular materials and cellulose 

 are notably acid resistant. 



Although a simple, universal fractionation procedure is obvio- 

 usly desirable, the intergradation of properties, and the great 

 variability which is to be found in the wall components of different 

 species or even in walls which are in different stages of differentia- 

 tion renders such an aim impossible or nearly so. Further, interest 

 in the isolation or removal of particular wall components in specific 

 tissues or organs has stimulated the development of many proce- 

 dures which are too gross for accurate, complete analysis. The 

 Cross and Bevan treatment is an example of an historically important 

 procedure. Whole cell wall material (wood for example) is treated 

 with chlorine and sulfites with the resulting solubilization of lignin 

 and polyuronides. The residue, known as Cross and Bevan cellulose 

 actually consists of true cellulose together with non-cellulosic 

 polysaccharides. Pure a-cellulose can be obtained from this residue 

 by extraction of the non-cellulosic component with cold 17.5 per 

 cent NaOH. 



