CHAPTER XII 



PHYSIOLOGICAL VALUES OF THE NUTRIENTS 



THE preceding discussion of the physiological uses 

 of the various nutrients has dealt largely with them 

 as classes. The special functions and relative values 

 of individual compounds within the same class or of 

 the different classes have not been considered. We 

 know, for instance, that the albuminoids are in a 

 general way flesh -formers, or fat -formers, or heat- 

 formers, but we desire still further information as to 

 the relative efficiency of the individual albuminoids for 

 any specific purpose. Are some albuminoids more use- 

 ful than others in aiding milk secretion ! Similar 

 knowledge concerning the non-nitrogenous nutrients is 

 important. How valuable physiologically is cellulose 

 as compared with starch ? 



Again, we are convinced that both the carbohy- 

 drates and the vegetable fats may 'be sources of animal 

 fats, but we are bound to inquire what is the relative 

 importance of these groups of compounds as fat- 

 formers in the animal body. 



It is easy to understand that knowledge of this 

 kind would be valuable. We are coming to know a 

 great deal about the composition of the various cattle 

 foods, and if we could ascertain the exact physiologi- 



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