EXAMINATION FOR SHELLS, HULLS, SKINS, ETC. 141 



b. Grains small with sharp edges, nucleus large : Millet starch. 



c. Grains rounded, polyhedral, occasionally gnarled, in columnar bundles, 



nucleus large: Buckwheat starch. 

 III. Grains very small, punctiform in appearance under 200 diameters magnifica- 

 tion: Lolium tevmlentum, corn cockle, chenopodium, notchweed and sev- 

 eral other weed starch grains. 



The starch grains of rye, wheat and barley are lenticular in form, sometimes 

 concentrically laminated, with central nucleus or nuclear fissure. The results ob- 

 tained from microscopical examination are not infallible. However, meal gruel (1 

 to 50) well stirred and carefully heated to 62.5° C. (144.5° F.), then rapidly cooled 

 and subjected to examination will show the wheat starch almost wholly intact (Fig. 

 73), while rye starch grains will be swollen and mostly ruptured (Fig. 72). Barley 

 starch exhibits a greater variety of form and more irregularity. 



The starch grains of corn cockle (Fig. 71) are flask or spindle shaped. Upon the 

 exertion of pressure they break up into innumerable polyhedral granules with 

 rounded edges and 1 micron diameter. 







© o 



Fig. 72. Rye flour heated at 62.5°C. (144.S°F.) Fig. 73. Wheat flour heated at 62. 5°C.(144.5°F.) 



Examination of By-Products Containing Shells, Hulls, Skins, etc. 



The contents of 4he various screens are spread out upon a sheet of white or 

 black paper. Particles of similar appearance are picked out with the aid of fine 

 forceps and laid aside for identification. Those that can not be identified with 

 the naked eye or with the aid of a magnifying glass are cleared by boiling for a 

 moment in a 1 to 2 percent solution of potash, strained through fine gauze, washed, 

 then similarly boiled in equal parts of glycerin and acetic acid, filtered and washed. 

 The residue is examined, with the aid of a teasing needle, under the microscope, 

 using 150 to 300 magnifying power. The material may also be successfully cleared 

 by light boiling for 30 minutes in 1.25 percent sulphuric acid in a flask with return 

 condenser. The product is washed, filtered, and the residue boiled for 30 minutes in 

 1.25 percent potash solution in a similarly equipped flask, then filtered, washed and 

 subjected to examination. Various species of weed seeds are easily recognized by 

 the dark color of their skins or membranes. 



In the following paragraphs a few of the most important feeding stuff's and their 

 most common and dangerous adulterations are briefly mentioned and illustrated. For 

 further and more detailed information and instruction the reader is referred to the 

 works already quoted under 1, 2 and 3. When doubts arise as to the exact nature 

 of certain substances, they may be compared with corresponding material of known 

 origin. 



In determining the character of these foreign substances due consideration must 

 be given to the question of whether they are naturally or accidentally present (e. g., 

 moderate amounts of weed seeds) or whether they were added with the intention to 

 defraud, or adulterate. In the former instance, when these substances are present in 

 limited amounts, and not of a toxic nature, no special objection can be made. 

 Poisonous substances or intentional adulterations are another matter. 



