236 AGRICULTURAL CHEMISTRY 



other non- nitrogenous bodies, as sugar, gums, pentosans 

 and organic acids, are also present. There is no regular 

 law as to the way in which the reserve food is stored up 

 in seeds. Even in the same family of plants, the nature 

 of this reserve food may vary between wide limits. 

 Starch forms the largest proportion of the reserve food of 

 the cereals. In oil seeds, as flax, rape and mustard, fat 

 is the main form of non- nitrogenous food. Since fat is 

 about 2.25 times more concentrated in fuel value than 

 starch, it follows that in oil seeds, a large amount of re- 

 serve material is stored up in a small space. Oil seeds 

 are, as a rule, small in size, but concentrated in both non- 

 nitrogenous and nitrogenous food. The cellular tissue of 

 seeds is composed of cellulose and pentosan materials. 

 The amount of pure cellulose is generally small. 



331. Nitrogenous Compounds of Seeds. The nitroge- 

 nous compounds of seeds are present mainly in the 

 form of insoluble proteids, as the glutens of the cereals. 

 Small amounts of other proteids, as albumin, globulin and 

 proteose, are also present, as well as some of the albumi- 

 noids, as nuclein, and a small amount of amide com- 

 pounds. In studying the carbohydrates, it was found 

 that starch was present in regular organized forms called 

 starch granules. In many seeds, particularly cereals, the 

 proteids also are present in organized forms called 

 aleurone grains. Under the microscope, the aleurone 

 grains look like crystals. They are not true crystals 

 because they are not built on a definite plan. An 

 aleurone grain consists mostly of proteid matter enclosed 

 in a nitrogenous envelope. The nitrogenous compounds 



