) 



f 



4: Feeds and Feeding. 



major portion of all dry plant substance. They are grouped un- 

 der the term carbohydrates, meaning formed of carbon and the ele- 

 ments hydrogen and oxygen in the proportion existing in water, 

 the chemical formula for which is H 2 0. The molecular composi- 

 tion of the leading carbohydrates is shown in the following for- 

 mulae : 



Glucose 



Levulose 



Cane sugar ) r 1 TT n 

 Maltose f u > o " 



Starch ) , r TT n w 



Cellulose f ^^^^ 

 Pentosan (C 5 H 8 4 )x 



Pentose C 5 H 10 5 



Chemists hold that the molecules in the bracketed groups are in 

 reality far more complex than the formulae indicate, the actual 

 molecule being many multiples of the group here given. The for- 

 mulas not bracketed are held to express the actual atomic compo- 

 sition of the molecule. 



All sugars sucrose, glucose, maltose, levulose, etc. are soluble in 

 the juices of the plant and constitute the common, portable carbo- 

 hydrate building material of plants, capable, by diffusion and sap 

 currents, of passing to all parts of the structure as needed. Some 

 plants, the beet and the sugar cane for example, store their carbon 

 reserve as sugar. Starch, however, is the common intermediate car- 

 bohydrate reserve of the plant world. It is insoluble in the juices 

 of the plant and so cannot be directly transported as can the sugars. 

 Starch abounds in most seeds, closely packed about the germs, as 

 in the kernels of wheat, Indian corn, etc. Often it is stored in the 

 underground parts of plants, as in potato tubers. "When the starch 

 thus stored is needed in other parts of the plant, it is changed by 

 a ferment called diastase, thru the addition of water, to maltose, a 

 soluble sugar, which can be further changed to glucose by the ad- 

 dition of more water. The sugars so formed can then be passed 

 from cell to cell until their destination is reached, where they may 

 be again changed to starch, pentosans, or cellulose, as required. 



Plants are primarily composed of minute cells, variously grouped 

 and modified, the walls of these cells being formed of cellulose. 

 Cellulose is the great permanent, insoluble structural substance of 

 the vegetable world, constituting as it does almost the whole of the 

 skeleton or framework of plants. As before shown, cellulose is 



