310 PROCEEDINGS OF THE ACADEMY OP [1883. 



granules. These may, to a large extent, be removed by immersing 

 the section for a short time in liquor potassfe, with subsequent 

 careful washing. The alkali affects the hydration and partial 

 solution of the starch; but if its application be too long continued, 

 the gluten will also be dissolved. This treatment is well adapted 

 to show the rather dense gluten networks usually found in bran, 

 immeiliately below the fourth layer. 



3. The most satisfactory^ method of studying the distribution of 

 gluten in sections of wheat is that of artificial salivary digestion. 

 If the section be gently boiled for a moment to hydrate the starch, 

 then transferred when cool to filtered saliva, and maintained for 

 from half an hour to an hour at a temperature of about 98° Fahr., 

 all the starch will be digested away, while the insoluble proteid 

 and other constituents will remain entirely unaltered. A section 

 of wheat grain thus treated will exhibit, throughout its entire 

 central portion, close-meshed gluten networks, which become 

 slightly denser toward the cortex of the grain. The proteid 

 character of these reticuli is here, as in the first method, sus- 

 ceptible of micro-chemical demonstration by Millon's reagent or 

 the biuret reaction. A relatively very faint coloration, indicating 

 the presence of albumenoids, is noticeable in the " gluten-cells," 

 while the gradual condensation of the gluten of tl;e endosperm as 

 the cortex is approached, is evidenced by a quite vivid coloration 

 of the fibrils. 



Schenji ' has applied Millon's reagent to sections of wheat with 

 a resultant assumption by the endosperm of a pink tint and " no 

 coloration of the cortical gluten-cells.'' The starch was not removed 

 and the method of distribution of gluten was not determined. By 

 artificial gastric digestion of wheat sections, the same observer 

 noted that the starch of the section became readily detached, and 

 deduced from this the just proposition that the gluten la}- between 

 the starch granules. 



Objections are not infrequently offered by the chemist to the 

 microscopical determination of organic compounds, especially 

 where any attempt at a quantitative estimation is made. All that 

 is claimed for the methods above described is the demonstration 

 of gluten in very considerable quantity in the inner layers of tlie 

 wheat grain. It is but just to state, however, that by these 

 methods a conception may be obtained of the quantity of protcids 



1 Anat.-Physiol.-Unters., p. 33. Wien,, 187i 



