12 



MICROSCOPIC CHARACTER OF MEAL. 



Maize flour is of a yellowish or white color and rough to the touch. 

 The starch is iu grains of a tolerably uniform volume. The minimum 

 diameter appears to be about 6 micromillimeters, while the largest may 

 reach as much as 17 micromillimeters. The greater part have diameters 

 of from 13 to 15 micromillimeters. The starch granules are polyhedric 

 in shape when they come from the external zone. They are of rounded 

 shape, on the contrary, in the floury zone. The upper face appears to 

 be somewhat spherical. The hilum is puuctiform and sometimes stel- 

 lated. The concentric layers are well marked and the fracture is most 

 frequently from the exterior toward the interior. Heated in water at 

 62.5 the starch granules swell up and become deformed, except a few - 

 especially the smaller ones which resist the action of water at that 

 temperature. 



In maize, as in oats, the starch granules are polyhedric, but the 

 resemblance extends no further, the maize granules being larger and 

 never becoming agglomerated and forming compound particles. Their 

 action also on polarized light is characteristic. The starch granules of 

 maize depolarize the light and present a black cross very marked and 

 very distinct when the field is obscure. This cross persists for a long 

 time when the field is illuminated little by little, and it is distinguished 

 much more easily and with an illumination much more pronounced than 

 that which suffices to extinguish this phenomenon in other common 

 starches. Nevertheless, this cross is not long visible when the field is 

 fully illuminated. With the selenite plates, by preference working on 

 a neutral field, the grains of starch of the maize are seen to be col- 

 ored red, with a green cross, or reciprocally. This coloration is very 

 brilliant. 



If the starch granules be treated with caustic potash, there is found 

 in the midst of the debris a number of amorphous cellules of the amy- 

 laceous tissue irregularly arranged, in which may sometimes be dis- 

 tinguished a final residue of the protoplasmic matter which surrounds 

 the starch granules. 



The glutinous cells of maize resemble those of rye. They are dis- 

 posed in a single row, quadrangular, a little rounded on the angles and 

 much thicker on the exterior side than on the others. The starch cells 

 of maize are easily distinguished from those of the rye by their form 

 and by their action on polarized light. 



COMPOSITION OF FINE MEAL. 



The composition of the ordinary Indian-corn meal produced by 

 grinding the whole grain and removing only the coarser bran is, as 

 has already been said, practically that of the whole grain itself. 

 Analyses of the refined Indian-corn flours show that they differ chiefly 

 from the whole grain in having a smaller content of fat, fiber, and 



