The Typical Cellulose and the Cellulose Group 77 



To sum up these more prominent points in the evidence of 

 constitution, we are entitled to regard cellulose as conforming, in 

 regard to its ultimate constituent groups, to the general features 

 of the simpler carbohydrates of well-ascertained constitution, 

 but differentiated by a special molecular configuration resulting 

 in a suppression of activity of the constituent groups in certain 

 respects, but on the other hand conferring greater reactivity is 

 others. This molecular configuration involves primarily the 

 question of the mode of arrangement of the carbon with the 

 qualifying hydrogen atoms within the unit groups which, for 

 the reasons given, may be assumed to be of the dimensions of 

 C 6 ; and, secondly, the grouping of these into the aggregate 

 which may be regarded as constituting the true molecule of 

 cellulose. Next in importance are those modifications of con- 

 figuration which are bound up with the disposition of the C 

 atoms. 



In regard to carbon configuration the evidences are rather 

 indirect than determinable by the actual properties of cellulose 

 itself. The choice obviously lies between a chain and cyclic 

 formula for the unit groups. The balance of evidence is in 

 favour of the latter and on the following grounds : (i) the 

 general differentiation of cellulose in regard to stability, which 

 points to a symmetrical formula, as distinguished from the normal 

 chain upon which the hexoses are represented ; (2) the for- 

 mation of a cellulose acetate of the composition C 6 H 6 O (OAc) 4 , 

 in which only 2n carbon valencies are taken up in ' outside ' 

 combination ; (3) the simple and manifold transitions of cellu- 

 lose in the plant world into keto R. hexene and benzene 

 derivatives. The process of lignification in the plant cell is 

 characterised by the formation of groups of the general form 



/CH=CH V 

 CO/ >CH 2 



X C C/ 



(OH) 2 (OH), 



