36 THE ELEMENTS OF PLANT FOOD 



Cellulose (C 6 Hi O 5 ) n . The n in this formula stands 

 for an indefinite number of multiples of the radical ex- 

 pressed. The molecule may contain twenty or it 

 may contain two hundred times the number of atoms 

 given in the formula. The chemical analysis may 

 show the same elements with the proportions as given, 

 but the substances may be very different in appearance 

 and may vary by the different ways in which these 

 elements come together, as well as in the number of 

 atoms in the molecule. 



Cellulose is found in every part of every plant. The 

 coarse wood of all trees and the tender shoots of the 

 most delicate plants contain cellulose. It constitutes 

 the outer wall of vegetable cells and is therefore an 

 essential part of all plants. Cotton, hemp, and flax 

 fibers consist almost entirely of cellulose. 



Cellulose may be dissolved in sulphuric or other acid. 

 If, then, the solution is heated under pressure, part of 

 the cellulose is changed into glucose. Thus it is apparent 

 that glucose may be made of sawdust, rags, and paper. 



Note. Paper in its many forms consists largely of cellulose. It 

 may be made from wood, rags, and straw. Whatever substance is 

 used, it is first finely divided or pulverized and boiled in a weak alkali. 

 This pulp mixed with water is poured over a steadily moving wire 

 cloth. The water passes through the cloth, leaving the sheet of pulp, 

 which, gradually drying, is passed over the drying cylinders, and is 

 then finished as desired. 



Starch (CeHioOs),, is found in grains of all kinds, and 

 it forms the largest part of the solid matter of many 

 vegetables. Starch is produced in the leaves of all green 

 plants during growth and is deposited and stored in the 

 roots, stems, and seeds or fruits. The starch of com- 



