Structure of the Wheat Kernel 229 



softer parts. We find, then, that in every wheat ker- 

 nel there are three coats entirely unlike the rest of the 

 grain, because they consist of hard, thick-walled cells 

 containing but little starch, if any, with a much larger 

 proportion of cellulose or fiber than is found in the 

 inner portion of the kernel. Figs. 4 and 5. 



Just inside the innermost of the three outer coats 

 is a layer of material very rich in protein compounds, 



Fig. 4 . Section of entire wheat kernel (enlarged 16 diameters). 

 1, Seed pod and seed coatings. 4, Gluten layer. 5, Mass of starch cells. 



which may properly be called the gluten layer. The 

 great bulk of the wheat kernel is made up of cells 

 closely filled with starch grains. This is the soft white 

 portion of the seed and is that which furnishes the 

 flour. All of these parts serve to protect, and, in ger- 

 mination, to nourish the essential portion of the seed, 

 the germ or embryo which lies " at the lower end of the 



