20 Notes from ike Physiological Laboratory 



by large numbers of starch-granules. These may, 

 to a large extent, be removed by immersing the sec- 

 tion for a short time in liquor potassse, with subse- 

 quent careful washing. The alkali effects the hy- 

 dration 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 net- works usually found 

 in bran, immediately 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 main- 

 tained for from half an hour to an hour at a tem- 

 perature 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 net-works, which become slightly denser to- 

 ward the cortex of the grain. The proteid char- 

 acter of these reticuli is here, as in the first method, 

 susceptible of micro-chemical demonstration by Mil- 

 Ion's reagent or the biuret reaction. A relatively 

 very faint coloration, indicating the presence of 



