230 AGRICULTURAL CHEMISTRY 



solid excrements. The animal body cannot produce 

 proteids from amides, or amides from ammonia. This- 

 elaboration or construction process can take place only in 

 the plant. The animal body can simply make over into 

 other forms, the proteids supplied in the food, or decom- 

 pose them and form amides and other products. 



-In animal tissues, many amides are produced during 

 fermentation and decay, as methylamine, the b'ase which 

 gives the characteristic odor of fish. Methylamine is also 

 found in rye fodder when the plant is at the heading- out 

 stage, and imparts a fishy taste to the milk of cows fed 

 upon such fodder. In meats, these compounds are 

 associated with other bodies, as ptomaines, which are of 

 a poisonous nature. Amides are also produced during 

 the digestion of food, and if the intermediate products 

 between proteids and amides are not completely oxidized, 

 poisonous substances are formed. 



317. Food Value of Amides. The amides do not 

 have a high food value compared with the proteids, and 

 cannot replace proteids in a ration. The amides possess 

 only a secondary food value, and, like the gelatin albu- 

 minoids, may to a limited extent prevent a rapid waste of 

 body tissue. Some give taste and character to foods, as 

 asparagin in asparagus, and in meats they are the bodies- 

 which give flavor. Some of the amides have medicinal 

 properties, while others are poisonous. 



318. Amount of Amides in Foods. In matured 

 grains, less than 5 per cent, of the total nitrogenous 

 matter is in the form of amides, and in meats there is 

 less than i per cent. In some foods, notably roots and 



