EXAMINATION FOR STARCH GRAINS 



137 



Sometimes Schaffnit's method is used to separate the various ingredients of meals 

 and brans. Schaffnit's agitator funnel (Fig. 56) is used by filling to at least half 

 capacity with chloroform and about 20 grams of meal or substance to be examined. 

 The funnel is then closed as shown in Fig. 56-A, thoroughly shaken, and set away 

 to allow contents to separate and settle. Sand, mineral matter and aleurone cells 

 sink to the bottom, and are separated from the other parts as illustrated in Fig. 

 56-B. They are released by removal of the lower stopper and subjected to exami- 



Fig. 56. Schaffnit's agitator funnel. 



nation. The lighter particles (skins, hulls, plant tissue, hairs, mites, etc.,) float on 

 the surface. They are removed with the chloroform and examined. 



Examination for Starch Grains 



For the examination of the starch grains the contents of the lowest compartment, 

 which contains the finest meal, are used. Meals rich in fat rnust first have the 

 latter removed by treating with ether, or alcohol and ether, to dissolve and remove 

 the fat. After removal of the fat the sample is mixed with water or diluted glycerin 

 to form a thin milky or turbid fluid. This material is used for the preparation of 

 microscopic slides to be examined with, and without the addition of a dilute iodin- 

 potassium-iodid solution. If the meals are of a cereal nature, examine for hairs, 

 note their length and compare thickness of walls with lumen. 



The starch grains and cells of the various species of grains and leguminous seeds 

 frequently have characteristic forms which alone may indicate their nature or 

 origin. 



The diameter of the starch grains of the most important species of grains are 

 given below. 



Microns 



Rye starch 37 to 53 



Wheat starch 28 to 40 



Barley starch 20 to 26 



Rice starch 6 



Oat starch 4 



Corn starch 20 



Pea starch 50 to 57 



Bean starch 33 to 63 



Lentil starch 33 to 67 



Microns 



Potato starch 60 to 185 



Peanut starch 4 to 25 



Acorn starch 10 to 30 



Horse-chestnut starch 5 to 26 



Millet starch 5 to 15 



Buckwheat starch 5 to 20 



Poisonous darnel 2 to 6 



Corn cockle 1 



