APPENDIX B 



659 



It is important as a basis for judgment of the results of milling to 

 know by analysis the distribution of the constituent substances in the 



Fig. 504. 



Part of a section of a grain of Wheat. £=pericarp; t = seed-coat, internal to 

 which is the endosperm; a/ = aleurone grains; «;w = starch grains; n = nucleus. 

 ( x 240.) (After Strasburger.) 



Wheat-Grain. This is shown by the subjoined table, taken from Dr. 

 Hutcheson's book on Food : 



A large portion of the grain (85 per cent.) is endosperm ; the bran 

 amounts to 13-5 per cent., and the germ only to 1-5 per cent. The 

 latter is, however, important, for it contains a high proportion of 

 proteins, of fats, and of ash. Since the germ flattens in roller-milling, 

 it can be sifted out. The highly nitrogenous and fatty body thus 

 extracted may then be added to ordinary flour in varying proportions, 

 giving different kinds of germ-bread. Bran is characterised by its 

 large proportion of cellulose and lignin (18 per cent.), which is indi- 

 gestible by man, but more available for herbivorous animals. There 

 is in it, however, a large quantity of nitrogenous substance, owing 

 to the adherence of the aleurone-layer of the endosperm to the flaky 

 scales of the fruit-coat ; the silica in the latter accounts for the large 

 percentage of ash in bran (6 per cent.). Thus bran contains an undue 

 proportion of proteins in which the grain as a whole is deficient. Its 

 value in bran-mash for horses is therefore easilv understood. The 



