STARCHES. 

 SECTION I. 



STARCHES. 



(1) Wheat Starch. 



Wheat starch (Fig. 1) is obtained from the fruits of several 

 species of Triticum, as, for instance, T. tativuin, Lam., etc. Like 

 some other starches derived from cereal grasses it is distinguished 

 by consisting principally of a mixture of a large number of very 

 small grains with others of much larger size ; intermediate grains 

 are comparatively rare. 



The small grains vary from 2/i to %/** in diameter, averaging 

 about 6/* or 7/w ; they are rounded or oval in outline, seldom 

 polygonal or pointed. 



The large grains in surface view appear sometimes rounded, 

 sometimes slightly irregular or oval, but when, by touching the 

 coverelip with the needle they are made to present their edges to the 

 observer, they are seen to be flattened or lenticular in shape. They 

 seldom exhibit any concentric striae or evident hilum. They 

 may attain as much as 45//. in diameter, but they average only 

 25/x, to 35/A. In side view they are elliptical or sometimes 

 spindle-shaped, and exhibit a longitudinal line that is always 

 simple and usually straight or slightly wavy. 



(2) Rye Starch. 



Eye starch (Fig. 2) is contained in the fruits of the rye, S(cale 

 cereale, Linn. Like wheat starch it consists of a mixture of very 

 small grains with large ones, together with a certain number of in- 

 termediate size. The large grains are discoid in shape, and often 

 exhibit irregular protuberances, in consequence of which their side 

 view is often less regularly fusiform or elliptical than it is in wheat 

 starch. They average 40/x in diameter, but may attain 50/x, and 

 are therefore larger than the grains of wheat starch. Sometimes the 

 concentric striae are indistinct, sometimes they are easily visible. 

 In the centre there is often a cavity with from three to five rays, 

 and in such case the hilum is said to be stellate. Amongst the 

 grains of medium and small size, hat-shaped and bell-shaped ones 

 are to be found ; these are very seldom seen in wheat starch. The 

 small grains of rye starch are also rather larger than the corre- 

 sponding grains of wheat starch ; they vary from 3/x, to 10/x, in 

 diameter. 



* Measurements of microscopical objects are generally expressed in mikra 

 a mikron, /*, is the one-thousandth part of a millimetre (O'OOl Mm.), 



