2o6 THE CARBOHYDRATES 



substances ; thus the process of Hgnification consists in the 

 conversion of cellulose into ligno-cellulose ; accompanying this 

 change is a gradual disappearance of the protoplasm. Thus 

 the protoplasm within the cell produces a number of different 

 substances which are deposited in the cell wall, the nature 

 and properties of the resulting fibre depending on the nature 

 of these substances. 



CLASSIFICATION OF CELLULOSES. 



The naturally occurring celluloses were originally classified 

 by Cross and Bevan in the following manner : — 



I. Typical or Normal Celluloses of the Cotton Type. — These 

 were exemplified by the cellulose obtained from cotton, flax, 

 hemp, etc. 



n. Compound Celluloses of the Wood Cellulose, Jute and 

 Cereal Grass Types. — The natural celluloses occurring in jute, 

 cereal straws, esparto grass, etc., were regarded as consisting 

 of some form of combination of cellulose with a non-cellulose 

 constituent, either of the nature of lignin in the case of 

 lignocelluloses, or a pectic or gummy substance in the case of 

 pectocelluloses, or a fatty substance in the case of adipocellu- 

 loses. This group was therefore subdivided into : — 



{a) Lignocelluloses, e.g. jute fibre. 



{h) Pectocelluloses, e.g. flax. 



[c] Adipo- or Cuto-celluloses, e.g. cork. 



HI. Hemi-, Pseiido- or Reserve Celluloses. — This hetero- 

 geneous collection of substances differ structurally from the 

 fibrous celluloses, and occur in the cell walls of the seeds of 

 various plants such as Coffea arabica, Soja hispida, Lupinus 

 luteus, Cocos nucifera, TropcBolum. majus, Impatiens balsamifera, 

 Pceonia officinalis, and in peas and beans. 



In this group of celluloses were also included those which, 

 according to the researches of Brown and Morris, are dissolved 

 by the enzymes secreted by the germinating seed ; these are 

 sometimes referred to as reserve cellulose, though the name 

 seems ill-chosen, inasmuch as they would not appear always 

 to function as reserve material. 



