66 THE PROTEINS OP THE WHEAT KERNEL. 



precipitates were united and distilled until one-third of the solvent was 

 removed. On cooling the residual solution, a deposit formed which they 

 considered to be a mixture of gliadin and mucedin. The solution decanted 

 from this deposit was evaporated to dryness, and yielded a considerable 

 residue of "mucedin." 



The analyses of these products showed that the gliadin thus prepared had 

 the same composition as that obtained by the writer, as well as that made 

 by Ritthausen, while the "gluten-fibrin" and mucedin contained about i 

 per cent less nitrogen and much more carbon. 



Konig & Rintelen obtained their mucedin from the nearly aqueous solu- 

 tions remaining after separating the gliadin by evaporating to dryness. The 

 writer assumes that the residue which remained was subjected to some fur- 

 ther purification, but concerning this they say nothing. The solution con- 

 tains many impurities, and when the protein substance in it has been 

 properly purified it has the properties and composition of gliadin. 



Although large quantities of gliadin have been made in this laboratory 

 and subjected to very careful and extensive fractionation, no evidence what- 

 ever of the existence of " mucedin " has been obtained. 



Furthermore, it would seem improbable that our gliadin could be con- 

 taminated by "gluten-fibrin" and "mucedin," which the writer certainly 

 did not succeed in separating from it, and at the same time show so close 

 an agreement in composition with that of Konig & Rintelen, from which 

 they suppose that both of these proteins had been carefully removed. It is 

 also improbable that Kjeldahl should have found the specific rotation uniform 

 for numerous preparations of the alcohol-soluble protein if the material 

 which he examined was a mixture of three different substances ; nor, if this 

 were the case, could his determination of (a) D 92 be expected to agree 



20 

 so closely with that made by Osborne & Harris, 1 ()^ 92.3, and by 



Mathewson, 2 (a) ~ 91. 95. 



The composition of both ' ' gluten-fibrin ' ' and ' ' mucedin ' ' differs from 

 that of gliadin just as one would expect if these former substances were 

 slightly altered, and somewhat impure products obtained from gliadin. 



Until more convincing evidence of the existence of " gluten-fibrin " and 

 "mucedin" as distinct protein substances is brought forward, they can not 

 be considered to be original constituents of the wheat kernel. 



Kutscher has stated that there is a wide difference in the proportion of 

 glutaminic acid which is yielded by gliadin and gluten-fibrin. The writer 



1 Osborne & Harris, Journal American Chemical Society, 1903, xxiv, p. 844. 



2 Mathewson, Journal American Chemical Society, 1906, xxxvin, p. 1482. 



