ORGANS OF DIGESTION. 69 



favourable temperature, a suitable mixture of fluids, and 

 plenty of mechanical movement, does not contribute to the 

 dissolution of the cell-membrane, which is wholly brought 

 about by the enzyme pre-existent in the grain " (Brown). 

 This writer (Proceedings of the Royal Society, 63, 1898, page 3) 

 has found that most of this enzyme exists in the inner layer of 

 the husk (aleurone layer). 



This enzyme of grain, like those animal enzymes, ptyalin 

 and pepsin, is a chemical substance, and is different from the 

 ferments produced by bacteria. According to Gamjee, the 

 activity of enzymes is destroyed by exposure to a temperature 

 of 126 F., which is a fact that probably explains the reason 

 why the feeding value of good oats becomes lessened by the 

 process of kiln-drying or parching. Barley, which either con- 

 tains very little of this enzyme or is wholly deficient of it, is 

 almost always improved by parching. 



Diastase is an unorganised ferment that converts starch into 

 malt-sugar (maltose) and British gum (dextrin), and thus 

 renders it soluble. Diastase is formed only during germina- 

 tion, as in malting. 



The reaction, as given by Bloxam, is : 

 3 C 6 H ]0 A (starch) + H 2 O = C^H^O^ (maltose) + C 6 H 10 O 5 (dextrin). 



Cerealin, which was discovered by Mege Mouries, is an 

 enzyme that occurs in bran. Its action is similar to that of 

 diastase, but is much slower. 



ORGANS OF DIGESTION. 



The irregularly shaped tube (the alimentary canal) 

 through which the food passes on its way into and out of the 

 horse's body, is formed by the mouth, gullet, stomach, and 

 intestines (small and large intestine), all of which organs are 

 lined by mucous membrane. This membrane also lines the air 

 passages (nostrils, windpipe, and bronchial tubes), bladder, 

 urethra (tube that carries the urine outwards from the 



