274 ECONOMIC BOTANY. 



in general, obtained. as follows: These are reduced between 

 large cylinders, and the pulp is washed in sieves. The starch 

 thus washed out is then dried in heated chambers, and 

 finally reduced between crushers. The pulp, in which more 

 or less starch remains, is used in feeding ; or from it starch- 

 sugar, or whisky is manufactured. Another mode is to slice 

 the bulbs, etc., macerate in warm water, and pile in heaps, 

 when fermentation takes place, by which, perhaps, the cell- 

 walls are dissolved — a process chemically not well under- 

 stood. The mass is then washed as above. From grains 

 (of wheat) the starch is obtained by crushing between 

 cylinders, after soaking the grains for ten or fifteen days, 

 then washing in sieves. Starch so obtained is not pure 

 white; therefore the following process is usually resorted 

 to : Water is added to the mass reduced as above, and 

 fermentation (first alcoholic, then butyric) takes place. 

 The starch is then washed, and found to be pure white. 

 Starch is used extensively as food. When green (not dry), 

 it is used in the manufacture of dextrine and sugar; when 

 dry, it is employed as paste for finishing cotton and linen 

 fabrics, as a thickener of colors and mordant in dyeing, 

 and for many other purposes. 



247. The Starch of Wheat, Triticum vulgare (family 

 Graminem), is in the endosperm of the grains. The grains 

 are (1) large and lenticular, the layers very indistinct or 

 invisible, the commonest size of which is .0011 inches; (2) 

 small and many-sided, and sometimes irregular, layers not 

 visible, with an average size of .00028 inches; and (3) com- 

 pound grains, composed of two to twenty-five easily-separa- 

 ble partial grains. The grains are distinguishable as such 

 with the aid of a lens. Those of wheat, rye, and barley are 



