﻿2 BULLETIN 1130, U. S. DEPARTMENT OF AGRICULTUEE. 



plate until the preparation is properly cleared. The clearing is com- 

 plete when the preparation beeonios transparent. Then transfer the 

 e ide to the stage of the microscope and allow it tc remain until no 

 movement is evident in the mom.u when viewed under the micro- 

 scope. Count the hairs and hah' fragments. The magnification 

 giving approximately ISO diameters here employed was obtained by 

 the use of compensating ocular 12 X and 16-millimeter apochromatic 

 objective. If apochromatic objectives are not available, an achro- 

 matic objective with an ordinary eyepiece giving the same magnifica- 

 tion is satisfactory. 



COUNTING THE HAIRS. 



The counting of a slide consists in the methodical enumeration of 

 all the hairs and hair fragments in the mount (Fig. 1). By means 



X 



Fig. 1.— Wheat hairs (X1S0) 



of the mechanical stage on the microscope, no difficulty is encoun- 

 tered in thoroughly and accurately covering the entire mount. Each 

 hair and hair fragment is given a value of 1, the final number being 

 taken as the value for the flour in question. 



SOURCES OF VARIATION IN METHOD. 



Department Bulletin 839 contains a full discussion of tests con- 

 ducted to determine the sources of variation in such a method. It 

 is evident that the variation in the counts made by two analysts is 

 greater in the case of bran particles than in the case of hairs. 



EXAMINATION OF MILL STOCKS. 



Modern milling processes consist essentially in releasing the floury 

 endosperm from the wheat grain, purifying it of bran substance, and 

 eventually reducing it to what is known as flour. Any manipula- 



