WHEAT. • 109 



bran of commerce contains about 75 per cent, of other 

 materials; that is to say, 15 per cent, of the nutritive 

 portion of wheat; otherwise bran would be practically 

 valueless as a food for stock. 



Within these envelopes, and next to them, is a row 

 of irregular, cubical cells. This row of cells is sup- 

 posed to be simply an expansion of the embryo and 

 has been called the embryonic envelope. The cells 

 are filled with phosphate of lime, and a solvent sub- 

 stance called cerealine, which assists in germination. 



The body of the grain or endosperm consists of large 

 thin- walled cells, filled mostly with starch but contain- 

 ing also gluten and other albuminous material. This 

 is the portion from which flour is made and is 75 to 

 80 per cent, of the whole berry. In the modern pro- 

 cesses of milling, besides the bran proper, the germ or 

 embryo, the embryonic envelope and seven per cent, 

 or more of the endosperm is separated from the re- 

 maining endosperm, the latter only being made into 

 flour. About 70 per bent of the berry is made into 

 flour. 



Chemical and Physical Properties.^- In 

 chemical composition wheat is very variable. It is 

 probably more susceptible in this respect to surround- 

 ing conditions than any other grain. 



The following may be given as the average of over 

 300 analyses of American wheat: 



Pounds 



Per Cent. per ton. 



Total dry matter 89.46 1789.2 



Albuminoids 11.80 236.0 



Crude fat 2.11 42.2 



Nitrogen-free extract (starch, etc.) 71.89 1437.8 



Crude fibre 1.80 36.0 



Ash 1.86 37.2 



