A GRAIN OF "FEDERATION" WHEAT 



Transverse section, enlarged about 400 times. The structures shown are as follows: 



(a) The epidermis, which consists of a layer of longitudinal cells with their long axes in the 



direction of the length of the kernel. 

 (6) Second layer, the epicarp, very similar to the former in general appearance resting on an 



irregular layer apparently devoid of cellular structure, 

 (c) The endocarp, placed at right angles to the cells above described. In cross section the 



cells of the endocarp appear to be very regular in character, with thick cell walls which 



in longitudinal section display minute pits. 

 {d) The testa, consisting in the unripe kernel of two distinct layers of cells closely applied to 



the aleurone layer. The testa is very tough in charater, not readily permeable to water 



and homogeneous in structure. 

 {e) The aleurone layer, consisting of large more or less rectangular cells, with thick cell walls 



containing oil and granular nitrogenous matter. It is frequently called the gluten 



layer, though this is a misnomer, as the gluten found in the flour is derived from the 



starch cells of the endosperm and not from the aleurone layer. 

 These five layers constitute the bran, and are usually removed when the wheat is milled. Be- 

 neath them are (f) the starch granules, which are ground up to make white flour. (Fig. 13.) 



