1902-3] The Chemistry of Wheat Gluten. 513 



gliadin. I have never been able to transform one of these compounds 

 into anything at all like the other. With the idea of finding out whether 

 gluten changed into gliadin, I extracted all the latter from flour, let one 

 half stand over night under water and the other under alcohol for 

 twenty-four hours, but neither yielded anything to dilute alcohol. 



The fact that ground, dried glutin mixed with starch yielded dough 

 of normal properties, as stated by Johannsen^^ is no proof as to the non- 

 existence of ferment action, since if ferment action were present the 

 dried gluten itself would have been the resultant product of the ferment 

 action. 



Flour was slightly moistened with absolute alcohol and heated on a 

 warm bath to 70° C, being stirred all the while with a stout thermome- 

 ter in order to heat the mixture evenly throughout. Alcohol was used 

 to prevent any possibility of ferment action. After drying in the air, one 

 half was taken and made into a dough, from which, as I expected, 

 gluten could not be obtained. A small quantity of raw flour was 

 intimately mixed with the other half and this was also made into 

 a dough. In this case also no gluten could be obtained. This proved 

 that the formation of gluten depended altogether on whether glutenin 

 was coagulated or not, since the ferment if existing should have been 

 present in the added raw flour. 



Now ground air-dried gluten mixed with starch and made into 

 dough yields gluten of normal properties. Such a dough of ground 

 gluten and starch warmed above 70° C. does not yield gluten since the 

 glutenin has been coagulated. Therefore when glutenin which had been 

 already made, as in the the second case , or glutenin, or even its pre- 

 decessor in the raw flour in the first case, was coagulated, a similar 

 result obtained. The probability, therefore, seems to be strong that 

 glutenin is present in flour as such. And since gliadin is extracted 

 directly from flour or bran with 70-95 per cent, alcohol, cold or boiling, 

 and also by dilute acids or alkalis, it also apparently is present as such 

 in flour, and not derived, as O'Brien^o holds, from the same parent sub- 

 stance as gluten. 



VI. — The Aleuron Layer of Wheat. 



The outer endosperm layer of wheat was stated by Sachs^^ in 

 1862 to be rich in oil and nitrogenous compounds. Ten years later 

 Pfeffer^^ pointed out the fact that gluten was not derived from the 

 aleuron layer as was commonly believed. He maintained that the high 



