360 PRINCIPLES OF AGRICULTURAL CHEMISTRY 



NITROGEN IN AMIDO COMPOUNDS 



Per cent. 



Asparagin 21.37 



Glutamin 19.31 



Leucin 16.87 



Phenyl-amido-propronic acid 8.48 



Tyrosin 7-73 



Considering that asparagin is the most common amide in plants, 

 it is evident that the factor 6.25 (which requires 16 per cent, 

 nitrogen) is too high. A percentage of 21.37 nitrogen requires 

 the factor 4.68. 



Inorganic Nitrogenous Bodies. Growing plants sometimes con- 

 tain appreciable amounts of nitrates or ammonia. Very little is 

 found in ripe seeds or plants. The nitrates or ammonia are 

 taken up by the roots of the plants, and used for the production of 

 organic nitrogenous bodies. 



Miscellaneous Nitrogenous Substances. Other nitrogenous sub- 

 stances found in plants are alkaloids, lecithin, chlorophyll, etc. 



Alkaloids are substances of poisonous or medicinal character. 

 Since they are bases, they unite with acids to form salts. 

 Alkaloids are not found to any extent in ordinary agricultural 

 products. 



Lupine seeds contain from 0.02 to 0.65 per cent, alkaloids, 

 according to the variety. The principal alkaloid is called lupinin. 

 The seeds are so bitter that, without special preparation, they are 

 not eaten by animals. 



Tobacco contains 0.61 to 6.44 per cent, alkaloids, the chief be- 

 ing nicotine. In the pure condition it is very poisonous. 



Caffeine is an alkaloid found in coffee and tea, to which they 

 owe a portion of their properties. 



Chlorophyll contains nitrogen, and so is included in protein. 



Nitrogen-Free Extract. 1 This term is used for the reason that 

 the material is soluble in acids and alcohols, and is free from 

 nitrogen. The nitrogen-free extract of seeds, and of many con- 

 centrated feeds consists largely of sugars, starches, and similar 

 substances, which are easily digested and of high value to animals. 

 But the nitrogen-free extract of hays, straws, and fodders con- 

 1 See Tollens, Exp. Sta. Record 8, p. 641. 



