BT MARGARET II. O'dWYER. 243 



tion therefrom will give incorrect results. This is the strongest and all im- 

 portant objection to any material change in a method for otticial endorsement" 

 (1916, p. 34). These writers have found that, by observing- certain precau- 

 tions, the results of the orticial method wilj cheek very closely, and the difli- 

 culties and tediousness will be eliminated. In fact, they have been unable to 

 make the determination by any of the proposed modifications in any less time 

 than by the official method. J. A. and E. W. Voelcker (1918) recommend a 

 modification of the official method involving the use of a 2% solution of the 

 acid and alkali instead of the 1.25% solution used by the American chemists. 

 Brunnich (1907) is of the opinion that Konig's method (1898) is superior to 

 the acid alkali method, and that the resulting crude fibre is free from pen- 

 tosans. Konig's method has, however, been unfavourably criticised by American 

 chemists, on account of its slow filtration and because of the variation in dupli- 

 cates. Brunnich, however, claims to have overcome these defects (Brunnich 

 and Smith, 1907). In a publication entitled "The Feeding Value of Cereals, 

 as calculated from Chemical Analyses" Chamberlain (1909) states that crude 

 fibre, though only slightly digestible, plays a very impoi-tant part in digestion. 

 "It acts as a dilutant," he says, "of the more concentrated jiortions of the 

 food, such its starch; necessitates for the whole food thorough mastication and 

 prevents it from becoming too compact; in other words it keeps the food 

 mass porous and open to the action of digestive fluids. If, however, the crude 

 fibre is in excess, the amount of energy expended by the animal in securing and 

 digesting the food is so great that its ultimate nutritive value is correspondingly 

 diminished." 



Ether Extract. — This contains, as well as fat, waxes, chlorophyll and some 

 of the organic acids. It is considered to be very impure in the case of the 

 coarse fodders, containing sometimes as much as one-half of non fatty sub- 

 stances. The method used for this estimation is again the American Official 

 metliod. Ward (1917, pp. 326 — 327) recommends that, in order to overcome 

 errore arising from the porosity of corks used in the Soxhlet apparatus and 

 the solubility of certain constituents of the cork in the extraction solvent, the 

 cork should be heated for two hours on a boiling water liath in a solution of 

 gelatin (previously soaked in cold water for five or six hours and then melted) 

 in a quarter of a volume of glycerol and two volumes of water. They may be 

 then removed, dried and employed in a Soxhlet apparatus for an hour. Thus 

 treated they may be used to advantage with any solvent in the vapour of which 

 water and glyceiol are not readily soluble. 



Pentosans. — In using the official American method for the estimation of the 

 pentosans in grasses, I am fortunate in having a small supply of phlorogluein, 

 which has been practically unobtainable. Should it not be forthcoming for 

 future determinations some other method must be substituted. That suggeste<l 

 by JoUes (1906) involves the use of orcinol which has also been difficult to 

 procure. Details of a third method which is a modification of the phenylhydra- 

 zine method have been given liy Menaul and Dowell (1919). Brunnich (1907) 

 recommends Tollens' (1902) method for the determination of pentosans, but 

 phlorogluein has, up to the present, been found so satisfactory a reagent that 

 other methods will hardly be adopted as long as it is available. 



Moisture. — This has been determined by heating the material to constant 

 weight in the water oven (Brunnich and Smith 1907). 



Ash. — In the determination of the ash, the American official method has 

 again been followed. 



