I 7 8 



AGRICULTURAL CHEMISTRY 





source. In hemp, it is flexible and tenacious, while in 



wood, it is hard and compact, in 

 the pith of the elder, it is elastic, 

 in the potato, porous, and in ger- 

 minating seeds, loose and spongy. 

 Cotton and filterjDa^er are ex- 

 amples of nearly pure cellulose. 

 The proportion and properties 

 of cellulose in a food influence 

 its digestibility. Some foods are 

 less valuable because of the 

 I tenacious character of the cellu- 

 Fi g . 73 . Flax fiber. lose, which prevents the cells 



from undergoing disintegration and digestion. 



229. Chemical Properties. Cellulose is composed of 

 carbon, hydrogen and oxygen. Its formula is C 6 H 10 O 5 . 

 Cellulose from one source may contain a different multiple 

 of C 6 H, O 5 than that from another source. In young and 

 growing plants, the cellulose is in a hydrated condition ; 

 that is, water is chemically united with the cellulose 

 molecule, as (C 6 H 10 O 5 .H 2 O) n . Hydrated cellulose is more 

 readily acted upon by chemicals than are other forms. 

 As the plant develops, the cellulose is gradually dehy- 

 drated and this is one reason why cellulose, at different 

 stages of growth, has a different food value. Ligno- 

 cellulose is found in wood and many mature plants. It 

 contains a larger per cent, of carbon than cellulose. 



230. Function and Value. In the plant, the function 

 of cellulose is to form the structural part of the cell walls. 

 It constitutes the main part of the walls of every plant cell. 



