76 The Feeding of Animals 



especially those most used by the human family, con- 

 tain it in generous proportions, in some seeds as much 

 as 60 or 70 per cent being present. Probably only water 

 and cellulose are more abundant in the vegetable world. 



Starch does not exist in solution in the sap, but is 

 found in the interior of plant cells in the form of 

 minute grains, which have a shape, size and structure 

 characteristic of the seed in which they are found. 

 Potato starch grains are large, about T^O of an inch 

 in diameter, and are kidney -shaped, while those of the 

 wheat are smaller, about ToVo of an inch in diameter, 

 and resemble in outline a thick burning-glass. Corn- 

 starch grains are angular, being somewhat six-sided, 

 and those of other seeds show marked and specific 

 characteristics. These differences in size and shape 

 furnish the most important means of detecting adul- 

 terations of one ground grain with another, as, for 

 instance, when corn flour is mixed with wheat flour, a 

 practice not unknown at the present time. 



Unless modified by some chemical change, starch is 

 not dissolved by water. The starch grains are not 

 affected by cold water, and in hot water at first only 

 swell and burst. Prolonged treatment with hot water 

 causes chemical changes to more soluble substances. 

 For this reason the simple leaching of a fodder mate- 

 rial removes no starch; at least not until fermentation 

 occurs. At the same time the treatment of a ground 

 grain with hot water so breaks up the starch grains 

 that they are probably acted upon more promptly by 

 ferments and digestive fluids, though perhaps no more 

 fully, than when not treated. 



