THE COATING -AND CELLULAR STRUCTURE 



OF THE WHEAT BERRY. 



7 WE have disposed now of the woody part of the grain, 

 . and have just reached the layer of cells, which is possibly of 

 the most interest to millers. A layer of large, nearly square 

 cells, with very thick walls and filled with fine granular mat- 

 ter, see Fig. i. The cells are 1-20 of a millimeter (1-500 of 

 an inch) in diameter, and quite uniform in size. The cell 

 walls are composed of several layers of cellulose, presenting 

 somewhat a laminated appearance under the microscope. These 

 layers can be separated from each other quite distinctly by boiling 

 in water for several hours or in a solution of caustic potash 

 for a short time. The granular contents are enclosed in sacks, 

 which are embedded in the cellular walls, as seen in Fig. 3, 

 where the two sacks have floated out of their usual resting 

 place. These sacks contain nitrogenous substances, and contain 

 them in much larger proportions than any other part of the 

 grain. If any means could be employed by which the grain 

 could be divested of all its coats excepting this last, and this 

 last coat could be treated in such a way as to separate the 

 nitrogenous sacks from, the framework holding them, and then 

 have the sacks form a part of the flour, we would probably 

 have the finest and purest flour possible. The process of scien- 

 tific milling has made such great advance during the past 

 twenty-five years, who can say but ere the next twenty-five 

 years pass, we shall have these microscopical sacks of nutrition 

 separated out from the woody part of the grain. The gluten, 

 or nitrogenous substances, exist in very minute particles, about 

 1-600 of a millimeter (1-15000 of an inch) in diameter. They 

 are insoluble in water, alcohol and glycerine, and are not 

 affected by iodine or potassa. Ammonio-nitrate of silver turns 

 them a dull yellow, while a solution of carmine turns them a 



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