MICROSCOPICAL DIAGNOSIS. 



slightly changed by dry heat, but is entirely destroyed by moist heat. 

 The grains found in the central or outer part of the kernel of corn 

 are more angular than those found in the inner part. This variety 

 is frequently substituted for wheat flour, under the name of "amy- 

 lum." 



Rice Starch. The starch grains of rice resemble very closely 

 those of corn. They are much smaller, however, being only -^^ of 

 an inch in diameter. The grains are angular ; being bounded by 

 plane sides only, are without rings, and have a central nucleus which 

 is either a dot, a line, or star-shaped. The grains are aggregated to- 



Fig. 34. Rice Starch. 



gether in angular or very irregular-shaped -masses. Rice is used 

 much more extensively in England as an adulterant than in America, 

 and commercial rice flour is frequently adulterated with corn starch. 



Oat Starch is the nearest like that of rice, and it is quite diffi- 

 cult to distinguish between them. Oat starch is both compound and 

 simple. The compound grains or masses are oval, spherical, or egg- 

 shaped ; the surface of the masses being smooth, while those of rice 

 are irregular. The divisions into grainlets show very distinctly. The 

 simple grainlets are larger than those of rice ; being T(T Vjr f an mcn 

 in diameter, and bounded by one or two curved faces. They are 

 without nuclei and without rings. A faint cross is seen with polar- 

 ized light. 



Buckwheat Starch is made up of both compound and simple 



