54 CHARLES ANTHONY GOESSMANN 



while the non-nitrogenous materials served merely as 

 the support of animal respiration. Liebig, on the other 

 hand, recognized that no single constituent of a plant 

 can support animal life neither nitrogenous matter 

 nor fat, neither sugar nor mineral substance: it re- 

 quires a certain definite proportion of each for different 

 classes of animals, and even for different conditions of 

 one and the same animal. 



To this period belongs the practice of classifying 

 agricultural fodder-crops by making hay the standard 

 for the determination of their relative feeding value. 

 At first this was merely a comparison of the market 

 values of different fodders; but later the basis of com- 

 parison was changed to make the chemical analysis of 

 good meadow hay the basis of the classification of 

 fodder crops. This method of comparison continued in 

 force for many years, but became more and more un- 

 satisfactory as a greater variety of fodder crops became 

 common. 



The efforts of these two leaders in rational agricul- 

 ture (Boussmgault and Liebig) to turn chemistry to 

 practical account in agricultural operations, soon led to 

 a more general introduction of agricultural experiment 

 stations. Much analytical work and many feeding 

 experiments conducted at these experiment stations, 

 showed that no one plant can furnish a standard for a 

 general fodder-valuation, and that no single definite 

 numerical expression can state the relative or absolute 

 feeding value of any fodder. Gradually it became clear 

 that a knowledge of the chemical composition of the 

 fodder articles alone was not sufficient to determine 



