CH. VIII, 5] ECONOMICS OF SEEDS 385 



close-packed cells of the original embryo, the food being 

 used partly in the formation of the root and partly in the 

 enlargement of cell walls. Evidently the functional point 

 of the process is found in the great spread of green surface 

 thus quickly achieved by the use of a relatively small amount 

 of solid material. The value of the spread of surface in this 

 case is obvious, for the young plant has to begin as early as 

 possible the acquisition of its own photosynthetic food supply. 



5. THE ECONOMICS AND CULTIVATION OF SEEDS 



Among all of the parts of plants, seeds stand preeminent 

 in direct utility to man. This of course is because they 

 include the grains, Corn, Wheat, Rice, Barley, Rye, and some 

 others, together with the leguminous crops, Beans, Peas, 

 Millet, which collectively make up the greater part of the 

 food supply of mankind. These seeds contain rich stores of 

 starches, oils, and proteins, originally laid down by plants 

 for the use of their embryos, and now taken for his needs by 

 man, who has been able through long centuries of cultivation 

 and breeding to greatly increase their yield both in quantity 

 and quality. Of a different kind is one other great economic 

 use of seeds, viz., the fibrous hairs developed by the Cotton 

 seed as its disseminative mechanism (by wind) yield the 

 cotton of commerce (Fig. 254). 



The grains, as earlier noted (page 349), are fruits as well 

 as seeds, the seed coat and ovary wall being grown together 

 into one structure which constitutes the husk. The husks 

 are removed in milling white flour, but retained in graham 

 flour, which is the more nutritious because it includes the 

 layer of protein-storing cells which form the outermost part 

 of the food in the grain (Fig. 65). 



The agricultural and horticultural treatment of seeds 

 appears to offer nothing peculiar, the various principles of 

 cultivation and breeding being the same as with other parts. 

 There is, however, one economic matter peculiar to seeds, 

 in connection with their viability. Since nothing in the 

 2c 



