COMPOUND CELLULOSES 155 



(#) Lignocelluloses. In the young cell the walls consist 

 of almost pure cellulose, but, as the cell grows older, the walls 

 may become permeated with what are known as encrusting 

 substances, the process being known as lignification. This 

 change takes place at the expense of the cellulose, and new 

 substances such as lignocellulose are produced. The extreme 

 limit of this change is the production of wood, which contains 

 only about 50-60 per cent of cellulose, while lignocelluloses 

 still contain about 70-80 per cent 



The lignocelluloses are considered by most authors to 

 consist of cellulose combined with at least two other non- 

 cellulose constituents ; one of these, A, appears to contain an 

 aromatic nucleus, and the other, B, contains a furfural-yielding 

 complex, and is possibly a pentosane. The two constituents, 

 A and B, are sometimes grouped together as a single sub- 

 stance under the name of lignin or lignone, which contains 

 50-60 per cent carbon, as compared with cellulose, which con- 

 tains only 44 per cent. 



According to Klason,* spruce wood consists approximately 

 of 50 per cent cellulose, 16 per cent other carbohydrates or 

 lignosans, 30 per cent lignin, and 4 per cent other substances. 

 The lignin would appear to be a condensation product of one 

 molecule of coniferyl alcohol (p. 187), with three molecules of 

 hydroxy coniferyl alcohol, having the formula C 40 H 42 O 12 ; 

 the union between the'se compounds is effected by the elimina- 

 tion of the elements of water between the hydroxyl of an 

 allyl alcohol group and the phenolic hydroxyl of another 

 molecule.f 



Doree and Cunningham,! on the other hand, are op- 

 posed to this view of the constitution of lignin, on the ground 

 that no vanillin results from the action of ozone on lignocel- 

 lulose, whereas this substance is produced readily by the oxi- 

 dation of coniferyl alcohol. 



According to Cross and Bevan (" Researches," III., p. 104), 

 the lignone complex is composed of a ketohexene group joined 

 by CH 2 CO groups to a pyrone ring with two methoxyl 



* Klason : " Arkiv. Kem. Min. Geol.," 1908, 3, No. 5, i, and 1917, 6, No. 15, i. 



fSee also Hagglund: id. t 1918, 7, No. 8, i. 



Doree and Cunningham : " J. Chem. Soc.," 1913, 103, 677. 



