ZEA 177 



Embryo. — In the normal flower, the embryo of corn is on 

 the side of the grain toward the tip of the ear. Inverted 

 grains have been found, however. This inversion is due to 

 the development of the lower flower of the pair in the pistil- 

 late spikelet. The embryo has the same structure as that 

 of wheat. On account of its large size, the parts are readily 

 made out. Its structure is best studied in a longitudinal 

 section cut at right angles to the broad surface. The pri- 

 mary root is conspicuous ; the two laterals may be recognized 

 as two swollen areas near its base. The scutellum, or single 

 cotyledon, is traversed by a vascular system. The hypo- 

 cotyl is just beneath the plumule, being terminated at its 

 base by the primary root. 



Color. — Purple, blue, black, and red grains owe their color 

 largely to a pigment located in the sap of aleurone cells. In 

 some grains, there is a red sap in the pericarp. There is an 

 absence of pericarp, aleurone and endosperm colors in white 

 corn. In yellow maize, the coloring matter occurs both in 

 the aleurone layer and in the endosperm. 



Com Starch Distinguished from the Other Common 

 Starches. — The following key, adapted from Winton's 

 Microscopy of Vegetable Foods, gives the characteristic 

 microscopic differences between the common commercial 

 starches. 



All or most of the grains rounded, not from aggregates. 



Grains rounded, with central hilum; small grains globular or angular. 

 Wheat. 



Grains large, of various shapes, with excentric hilum, Potato. 

 Grains polygonal or rounded, with one or more facets, mostly from aggregates. 



Grains very small, sharply angular, Rice. 



Grains large, polygonal or rounded; hilum with clefts, Maize. 



Germination of Com. — The germination of corn may be 

 judged from the following data: Sachs says: optimum 9i°F., 



