56 



THE CEREALS IN AMERICA 



maize grain ; otherwise it does not differ materially in structure 



from that of wheat. (63) It contains a slightly greater per* 



centage of protein, considerably greater 



percentage of carbohydrates and a much 



less percentage of ash and fat than the 



embryo. 



228. The Hull. — In dent maize the 

 hull, including the cap at the base of 

 the grain, constitutes, according to Hop- 

 kins,^ about seven per cent of the grain. 



The hull is easily removed from the 

 aleurone layer after soaking in hot water 

 for fifteen minutes. The pod or pericarp, 

 the integuments or testa, and the nucellus 

 or perisperm, which constitute the hull, 

 are not easily separable and cannot be 

 distinguished except upon microscopic 

 examination. (67) In the ripened grain 

 the pericarp forms the larger part of the 

 hull, the testa being compressed and the 

 nucellus much reduced.^ While under the microscope, the hull 

 appears to be composed chiefly of cell walls or cellulose, Voor. 

 hees* reports the following composition of the dry substance j 

 Ash, 1.3; protein, 6.5 ; fiber, 16.2; nitrogen-free extract, 74.4; 

 fat, 1.6. The nitrogen-free extract of the hull appears to bt? 

 largely gum (pentosan) rather than starch. 



229. Color. — A very large variety of colors is known to occur 

 in the grain of different types of maize. The most common 

 colors of all types except sweet maize are yellow or white or 

 some shade between. In this case the color is due to that of 

 the endosperm and possibly also the aleurone layer, but is not 



Cross section of the outer pof 

 tion of a grain of maize; p 

 pericarp ; t, testa or integu 

 merits; n, nucellus; a, aleu 

 rone layer; s, endosperm 

 (adapted from Webber). 



1 111. Bui. 87, p. 83. 



2 Iowa BuL 54 (1901), p. 132. 

 ' 111. BuL 53, p. X40L 



