160 F'lELD CROPS FOR THE COTTON-BELT 



icle surrounded by a root-sheath, a short hypocotyl and a 

 simple cotyledon, that encloses the tightly rolled plumular 

 leaves. The embryo is characterized by a high percentage 

 of oil, protein, and ash. It is situated 

 on the side of the kernel toward the 

 tip of the ear. 



The endosperm consists of the store 

 of reserve food surrounding the em- 

 bryo. It comprises the biggest portion 

 of the kernel (73 per cent) and is char- 

 acterized by its high percentage of 

 starch, although more than 50 per cent 

 of the total protein in the kernel is in 

 the endosperm. Hunt states that the 

 endosperm of corn contains 6 to 10 



FIG. 24. Cross sec- r no 



tion of the outer per cent of protein, 89 to 93 per cent 

 of carbohydrates (principally starch), 



t, testa or integu- an( j i ess than one-half per cent each of 



ments; n, nucellus; 



a, aleurone layer; ash and fat. 



The aleurone layer is composed of a 

 layer of cells lying between the hull and the endosperm 

 (Fig. 24). It is characterized by its rather high per- 

 centage of protein. 



The hull comprises the outer coverings of the kernel 

 and consists of (1) the pericarp which forms the greater 

 part of the hull and (2) the testa which is a layer of much 

 .compressed cells immediately underneath the pericarp. 

 . The layers comprising the hull are composed largely of 

 cellulose material. 



