REVIEW OF THE LITERATURE. 1 3 



Snyder 1 determined the amount of the different proteins in various flours 

 and mill products. He found 73.9 per cent of the total protein to be 

 gliadin in patent flour from soft winter wheat and 63.7 per cent in that from 

 hard winter wheat. He concluded that the protein in the gluten of a flour 

 good for bread-making consists of 65 per cent of gliadin and 35 per cent of 

 glutenin. The ratio of gliadin to glutenin in different grades of flour varies 

 between 1 to 4 and nearly 2 to 1 . While the lower grades of flour contain 

 more protein than the higher, the proportion of gliadin to glutenin is not 

 such as to produce bread of the best physical properties. 



Osborne & Campbell 2 found that the leucosin, globulin, and proteose, 

 obtained in very small quantity from the entire wheat kernel, together con- 

 stitute nearly the whole of the protein of the embryo, and that gliadin and 

 glutenin, which are the principal proteins of the endosperm, could not be 

 obtained from the embryo. The details of this investigation are given in 

 full in subsequent pages of this paper. 



Kossel & Kutscher, 3 following Ritthausen's directions, prepared the pro- 

 teins of wheat gluten and determined the proportion of basic products which 

 they yielded on decomposition with acids. They found that glutenin was 

 sharply distinguished from the protein soluble in alcohol by the fact that it 

 yields a notable quantity of lysine, whereas all their products derived from 

 the alcoholic extract of gluten yielded none of this diamino-acid. They 

 held the view, advanced by Ritthausen, that in gluten there are three pro- 

 tein substances soluble in alcohol. Of these mucedin yielded 3.13, gliadin 

 2.75, and gluten-fibrin 3.05 per cent of arginine and 0.43, 1.20, and 1.53 

 per cent respectively of histidine ; but in view of the methods employed 

 for the determinations of these bases they consider these differences too 

 small to justify the conclusion that these are distinct protein substances. 



Dennstedt 4 decomposed " wheat fibrin " by boiling with baryta and found 

 that one-third of the nitrogen was split off as ammonia and one-fifth of the 

 sulphur as sulphide and sulphate. After removing the barium and treating 

 the solution with lead acetate he separated proteoses, which he analyzed. 



Osborne 5 made careful determinations of total sulphur in four samples of 

 thoroughly purified gliadin and found an average of 1.027 percent, of which 

 0.619 per cent was split off as sulphide by boiling with caustic alkali. 



1 Snyder, Minnesota Agr. Exp. Sta., Bull. 63. 1899. 



2 Osborne & Campbell. Journal American Chemical Society, 1899, xxi, p. 486. 



3 Kossel & Kutscher, Zeitschrift fur physiologische Chemie, 1901, xxxi, p. 165. 

 4 Dennstedt, Chemiker Zeitung, 1901, p. 5. 



5 Osborne, Journal American Chemical Society, 1902, xxiv, p. 140. 



