THE NITROGEN-FREE EXTRACT OF FEEDING STUFFS. 061 



deliuite substances of fixed composition but quite variable mixtures; 

 and the method does not i)ei'mit of the exact separation of these 

 mixtures from one another. 



The nitrogen- free extract is a comphcated mixture of many difit'ereut 

 substances, in which the carbohydrates predominate; and the sejia- 

 ration of the nitrogen- free extract from the crude fiber, likewise a 

 mixture, is quite incomplete. 



In spite of all these ditliculties, the Weende method has rendered a 

 great service to the science and practice of nutrition of man and 

 animals, and it may be used in future until a better method is found. ^ 



In conclusion, a statement made by Ilenneberg himself in regard 

 to the value of his method of analysis may be cited, because it is 

 apparent from it that Henneberg clearly recognized the weaknesses 

 as well as the advantages of his method. In the autograph manifolds 

 of his lectures, which he was accustomed to distribute among the 

 students attending his lectures, Ilenneberg says (p. 43): ''In order to 

 ascertain the value of a feeding stuif for nutrition, it is necessary to 

 determine the content of all the separate constituents, or at least 

 of all the grou^is of similar value, and so far as the cellulose is con- 

 cerned, the various modifications of the same. These requirements 

 the customary analysis of ^■eg•etable feeding stuffs by no means ful- 

 fills." And he adds (p. 44): ''The present method of fodder analysis 

 needs greatly to be perfected, but in many respects accomplishes more 

 than would be expected from its defectiveness." 



'In a recent pnhlic.ition (U. S. Dept. Agr., Office of Experiment Stations Bui. 

 No. 21, pp. 46-48) Atwater makes a similar statement in regard to results by the 

 Weende method. Ho points out the indefinite nature of the crude fiber and the 

 nitrogen-free extract, and their very mixed diameter, and enijihasizes the great 

 desirability of new and reliable metliods for Uie analysis of feeding stufls. 



