640 EXPERIMENT STATION RECORD. 



against makiug a too wide application of the method devised for fod- 

 der analysis, and recommended the determination of smaller and more 

 definite groups of substances. 



Professor Tollens recommends that tlieWeende method be continued 

 in use until a better method is elaborated, supplementing it by determi- 

 nations of the aqueous .extract of the i^entosans. He points out that 

 the determination of aqueous extract, which is very simple, would add 

 considerable approximate information wliicli would be of value in judg- 

 ing of feeding staffs. For instance, he shows that the aqueous extract 

 corresponds approximately to the digestible nitrogen-free extract, and 

 that the sum of the digested crude fiber and the digested nitrogen free 

 extract agrees fairly well with the total nitrogen free extract; hence 

 the difference between the total nitrogen free extract and the aqueous 

 extract is approximately equivalent to the digestible cellulose. Where 

 more explicit information is desired as to the various constituents of 

 the nitrogen free extract, he recommends that the sugars, starch, 

 organic acids, etc., be determined by the customary methods. 



It is gratifying to note that two methods for determining the different 

 constituents of this indefinite grou^) of constituents have recently been 

 described l)y chemists in this country. A method by W. E. Stone, 

 noted elsewhere, enables the determination in the same sample by a 

 proper sequence of the sucrose, inveit sugar, dextrin, soluble starch, 

 normal starch, pentosans, and crude fiber. With this method, som.e- 

 what modified by use, some determinations have been made of the vari- 

 ous carbohydrates of wheat, flour, corn, and bread made from tlie same. 

 Another method, recently described by H C. Sherman, separates tlie 

 carbohydrates in a similar manner into soluble carbohydrates, starch, 

 free pentosans, liguin and allied substances, and cellulose. 



Neither of these methods has been tested to any considerable extent, 

 and possibly neither of them will be found to entirely answer the pur- 

 j)Ose when subjected to a practical test; but if they serve to stimulate 

 attempts to apply the results of recent investigation to the more 

 rational analysis of feeding stuffs, they will have served an excellent 

 purpose. Tliey open up the way for investigations of this character at 

 the experiment stations, not only in testing and improving the methods, 

 but in making practical application of them in feeding experiments on 

 the digestibility and the nutritive value of feeding stuffs — /. r., in deter- 

 mining the nutritive value and functions, not of an indefinite and vary- 

 ing mixture like the nitrogen-free extra -t, but rather of such definite 

 and widely distributed groups as sugars, starch, pentosans, cellulose, 

 etc. This is highly important if progress is to be made in studying the 

 fundamental problems of nutrition. Subsequent investigations may 

 enable the combining of certain of these groups, but for the present a 

 larger number of more definite groups of ingredients should be taken 

 into account. 



