THE CEREALS IN AMERICA 



unripe grain within two layers of cells, the inner and outei 

 integuments of the ovulary. In the mature grain the inner 

 integument may have been absorbed, leaving only the outer, 



known as the testa. 



.^^ 



Cross section of grain of wheat on the left. (From micro- 

 photograph by Toiman.) Transverse section, on the 

 right, of an unripe grain enlarged about 100 times 

 from drawing by Bessey. I, ovary wall or pericarp; 

 2i outer integument ; 3, inner integument; 4, remains 

 of nucellus ; 5, ale-jrone cells ; 6, starch cells. 



The testa is in turn 

 enclosed by the peri- 

 carp, corresponding 

 to the pod in the 

 pea. The pericarp 

 is composed of three 

 rows of cells and con- 

 stitutes a rather larger 

 portion of the grain 

 than do the testa and 

 nucellus together. 

 These envelopes are 

 sometimes spoken of 



collectively as the bran. Bessey ^ and Snyder ^ give different 



portions of the wheat grain as follows : 



Per cent 



Embryo 6-7 



Aleurone layer 3-4 



Endosperm . . . . . . .82-86 



Seed covering or bran ..... 5 



Girard gives the per cent of embryo in four varieties of wheat 

 as 1.50, 1.4 1, 1.35 and 1.16 respectively.^ 



Since the mill products of wheat average considerably less 

 than nine per cent crude fiber, and since seventy per cent of a 

 wheat grain is converted into flour, it follows that the seed 

 coats of the wheat grain must either be considerably less than 



1 Neb. Bui. 32, p. III. 



i Harry Snyder: The Chemistry of Plant and Animal Life, p. 278. 



3 Compt. Rend. Acad. Sci., Paris, 124 (1897), p. 878. 



