78 CELL CONTENTS. 



It will be noticed that in the above illustrations the cells inclos- 

 ing starch, etc., belong to the Cellular Tissue. 



FURTHER PREPARATION : The coats above named and their com- 

 ponent cells will be more clearly understood if two or three thin, 

 tangential sections be made, i. e., sections parallel to a plane tang- 

 ent to tbe surface of the grain, and extending only to the starch - 

 cells. Trace here the Aleurone cells, the Outer seed-coat (1'rimine), 

 the Endocarp, the Exocarp. If iodine be applied to either the 

 transection or the tangential section, and be followed by strong 

 sulphuric acid, the inner seed-coat, the Endocarp and Exocarp turn 

 a deep blue (the reaction for cellulose), then dissolve, leaving the 

 brown Outer seed-coat entire, thus indicating the corky nature of 

 the latter. 



The above study should be made with care as all cereals show 

 the same relative arrangement of seed-coats, aleurone-cells, and 

 starch-bearing cells. It will make more clearly understood some of 

 the processes of "high milling," by which the nitrogenous com- 

 pounds (the Aleurone grains), are separated and saved from the 

 bran. The ovary and seed-coats form the bran proper; the aleu- 

 rone-sacs contain most of the nitrogenous compounds or albumin- 

 oids, and the phosphates; the interior cells contain the starch, 

 which makes up the bulk of the "white" flour. 



For figures illustrating the structure of the coats of the wheat- 

 grain, see Report of the II. S. Com., at Vienna Ex., 1873, vol. 11, 

 p. 4, on Art on Vienna Bread ; Goodale, p. 47, 181 ; Strasburger, p. 

 19; Vine's Text Book of Bot., p. 112; Landois and Stirling, 

 Human Phys., p. 444. 



Illustration Fifth: STARCH. Grain of INDIAN CORN. (Zea 

 Mays.} 



The semi-transparent portion of the dry grain should be used, 

 and the sections made very thin and necessarily minute. The cells 

 of the seed should be observed, but particularly the form of the 

 starch-grains and the peculiar stellate cavities at the center of some 

 when the section is first mounted in water. For figures, see 

 Sachs' Botany, p. 61; Goodale, p. 181; Bessey, p. 55; Strasburger, 

 p. 12; Vines Text Book of Bot., p. 112. 



Illustration Sixth: STARCH in COMPOUND GRANULES. GRAIN 

 of OATS. (Avena sativa.) 



