DEVELOPMENT OF KERNEL 53 



this shank varies. In rank growing corn it will be higher than on 

 plants produced on poor soil. In a wet season, when the fibro-vascular 

 bundles are constantly supplying plant food from below, "shoots," 

 so-called, may appear at seven or more nodes, beginning quite near 

 the ground. The position of the shoot which finally matures is an 

 inherited character and it has been shown that it may be largely con- 

 trolled by selection. As a rule, it develops at a point between four 

 and six feet from the base of the stalk. Some varieties produce two 

 or more ears on each stalk. In favorable years, two ears per stalk are 

 not uncommon in many fields. 



THE KERNEL. DEVELOPMENT OF. In the study of the 

 development of the kernel, the first period of growth includes what 

 is commonly referred to as the milk stage. Kernels in the milk are 

 very sweet, due to the presence of sugar which has not yet been 

 transformed into storage starch. The protein, ash, and oil are depos- 

 ited in the *embryo (germ) before the endosperm or the body of the 

 kernel is filled out. Later, the cellular structure (endosperm) sur- 

 rounding the embryo is packed full of starch. Much of this material has 

 been held in readiness in the stalk and is now deposited in the grain. 

 A seed such as corn in which the reserve food is stored outside of the 

 embryo is said to be endospermous ; one in which the food is stored 

 entirely within the embryo is said to be exendospermous. The stor- 

 age of all this readily available food material takes place during the 

 development of the seed. Man has taken advantage of these facts 

 and developed in certain grains an increased storage of one or all 

 these constituents. The matured grain-fruit (kernel) is called cairy- 

 opsis. It is the ripened ovule surrounded by the ovary walls. 



Immediately covering the food supply of the seed and enveloping 

 the entire caryopsis, is a thin membranous layer called the tegmen 

 (seed coat), overlain by a tough cost or testa (ovary wall). The 

 integument formed by the union of these two constituents is the bran 

 of wheat and the hull of corn. It may be removed after soaking the 

 kernel in warm water for about twenty minutes. 



Germination is the resumption of growth of the young plant which 

 lies within the seed. This young plant is the embryo or germ.* It is 

 made up, first, of a large shield-shaped portion (scutellum) which 

 lies next the endosperm and which does not appear above ground, and 

 second, a portion which develops into the roots, stem, and leaves of the 



*This term embryo is sometimes loosely applied to that portion of the embryo which produces 

 the roots, stems and leaves. This is incorrect, the terms germ and embryo are strictly 

 synonymous. 



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