54 Notes from the Physiological Laboratory 



"gluten-cells' 7 undisturbed, closely adhering to the 

 cortical protective layers. 



By now carefully washing the white extruded 

 mass, the major part of the starch may he removed; 

 and, upon the addition of a drop of iodine solution, 

 microscopic examination shows numerous net-works 

 of fine yellow fibrils, still holding entangled in their 

 meshes many starch-granules, colored blue by the 

 iodine. 



In carefully washed specimens, the sponge-like 

 net-works are seen to retain the outline of the central 

 starch-filled cells, and evidently constitute the pro- 

 toplasmic matrix in which the starch -granules lay. 

 Upon gently teasing such a specimen under a mod- 

 erate amplification, the fibrils will be seen to become 

 longer and thinner in a manner possible only to 

 viscid and tenacious substances, a class represented 

 in wheat by gluten alone. 



An eminently satisfactory proof of the proteid 

 nature of these central net- works may be obtained 

 by heating the specimen in the solution of acid 

 nitrate of mercury (Millon's reagent), when the 

 fibrils will assume the bright pink tint characteristic 

 of albuminoids under this treatment. The results 

 of the application of the xanthoproteic and biuret 

 reactions are equally conclusive, but more care is 



