view. w hich is located on the opposite side of the furrow or crease 

 and at the end opposite to the brush or hairy tip, forms only a 



11 small part of the kernel. The grain varies in size and shape 



12 with the type and the variety. 



COMPOSITION. 



Variety, climate, and soil are the principal factors which 

 determine the composition of the wheat plant. Normally the 

 grain of wheat contains about 10 per cent of water, 2 per cent 

 of ash, 12 per cent of protein, 2 per cent of fiber, 72 per cent of 

 nitrogen-free extract, and 2 per cent of fat. The gluten is 

 made up from the protein and the starch content is included 

 under nitrogen-free extract. The gluten is a mixture of two 

 proteids, gliadin and glutenin, and its quantity and quality 

 determine the value of the grain for baking purposes. The 

 quality of the gluten is governed to some extent by the pro- 

 portion of gliadin and glutenin a gluten consisting approxi- 

 mately of one-fourth glutenin and three-fourths gliadin being 

 considered most satisfactory. The starch is located almost 

 wholly in the endosperm, which constitutes about 75 per cent 

 of the entire kernel, and nearly all of which is made into flour in 

 the process of milling. The nitrogen-free extract is largely 

 made up of starch, the amount of which varies from 60 to 70 

 per cent. 



Ordinarily the straw, including the chaff, constitutes from 

 50 to 65 per cent and the grain from 35 to 50 per cent of the 

 wheat plant. The straw contains normally from 10 to 15 per 

 cent of moisture, and in addition approximately 4 per cent of 

 ash, 3.5 per cent of protein, 40 per cent of crude fiber or cel- 

 lulose, 45 per cent of nitrogen-free extract, and 1.5 per cent 

 of fat. The chaff contains more phosphoric acid and also a 

 little more protein but less crude fiber than the straw. 



TYPES AND VARIETIES. 



The varieties of wheat are divided into groups according to 



13 botanical characters, and in some cases these again are divided 



14 according to characteristics due to environment or geo- 

 graphical distribution. 



Owing to the wide geographical distribution of the plant, 

 the varieties of wheat are more numerous than those of any 

 other cereal except rice. In addition to the botanical classi- 

 fication, a number of other classifications are in use, as, for 

 instance, the market classification embracing the different 

 types recognized by the grain markets, such as soft winter, 

 hard winter, hard spring, and white wheats; the classification 

 based on external characters, which groups the varieties into 



