1 66 Cellulose 



an ' aggregate ' method it is open to a good deal of objection ; and, 

 with the general advance of chemical and physiological methods of 

 observation, the time has come for a revision of the subject, in 

 order that the line separating * digestible ' from ' indigestible ' 

 matters may be defined more in accordance with directly ascer- 

 tained facts. 



In order to show in general terms the nature of the constituents 

 'digested,' i.e. dissolved by the artificial process, we give an abstract 

 of a report upon ' Determinations of Crude Fibre and their 

 Defects,' by C. Krauch and W. v. d. Becke, Landw. Vers.-Stat. 

 27, 5 (1882). 



The residue from the treatments by the Weende method is 

 generally assumed to be * cellulose and woody fibre,' and, by in- 

 ference, that these constituents resist the attack of the boiling acid 

 and alkali. These authors determined the proportions dissolved 

 from typical food-stuffs by the two treatments, together with the 

 elementary composition of the aggregates, with the following 

 results : 



(a) Dissolved by the boiling dilute acid ; (b] by the alkali ; and 

 (c) residue. 



() (*) (c) 



Rye (gram) .... 52-12 26-48 21*40 



Meadow hay .... 28-30 21-85 49*85 



Clover hay .... 19-47 26-17 54*36 



Elementary Composition of Aggregates 



(a) (b) Residue 



The above results are calculated with exclusion of the nitrogenous 

 constituents (albuminoids) and ash. From the high C percentage 

 of the constituents dissolved, it is evident that the lignocelluloses 

 are attacked. 



In more direct criticism of the assumed digestibility of the 

 'N-free extractive matters,' the authors investigated cereal 'meals.' 

 The starch was estimated by the malt extract process, and the 

 * N-free extractives ' by the Weende method, with the following 

 results : 



