180 MASS. EXPERIMENT STATION BULLETIN 187. 



cided influence upon the slime produced. Whether the machine is run 

 at high speed or low speed, whether the temperature of the milk is high or 

 low, whether the machine has passed quantities of milk or only a small 

 amount, whether it is one size or another and whether it is one make or 

 another, — all exert a modif jang influence on the amount of slime thrown 

 out. 



If, for instance, the amount removed when it is greater in one case than 

 in another is to the credit and efiiciency of the machine, wiU depend on 

 whether the material so removed is dirt or some normal content, as 

 leucocytes. However, it would seem that in the light of the primary 

 purpose of a clarifier the greater the amount of slime removed the better. 

 This will have to be passed over, however, for it has not been the object 

 of the writers to test the efficiency of clarifiers of different manufacturers, 

 or even the different makes of a single manufacturer. This has been 

 studiously avoided. 



Food Value of Slime, 



The average amount of slime estimated in terms of the entire milk is less 

 than five one-hundredths of 1 per cent. This weight includes foreign 

 elements, as dirt, hairs and such other materials as are likely to find their 

 way into the milk. Only the normal elements, as the so-caUed leucocytes, 

 the so-called fibrin, fat and casein, can in any sense be regarded as possess- 

 ing food value. Inasmuch as the 3| per cent, of fat and the 3 per cent, 

 of casein existing in slime (see analyses below) represent only 3^ and 3 per 

 cent, of five one-hundredths per cent, of the milk, in other words, .00175 

 and .0015 per cent, of the milk, the conclusion of analysts, that the 

 food value of slime is neghgible, is warranted. There is interest attached, 

 however, to the seeming fact that the protein not only comes from 

 the casein that is thrown out, as suggested by Mclnerney, but that it 

 takes the form of purin bodies, too, as suggested by North. The fat also 

 appears not only to be the fat of milk but, as Bahlman states, the fat of 

 epithelial cells and other detritus. Evidently the cellular elements fur- 

 nish a recognizable source of some of the material or substances found in 

 the slime; hence, when taken together with the large number of corpus- 

 cular elements eliminated in the slime which will be shown later, they 

 cannot be overlooked in the interpretation of milk clarification. This 

 raises a question at once, which, so far as the authors are aware, has not 

 been answered: Do these cellular elements in any manner contain a con- 

 stituent or constituents which contribute to nutrition? The work of' 

 McCoUum and Davis, ^ McCoUum, Simmonds and Pitz,^ Osborne and 

 Mendel,^ Hopkins and Neville,* and others suggests the possibihty that 



1 McCollum, E. v., and Davis, M.: The Nature of Dietary Deficiencies of Rice. Journal of 

 Biol. Chem., 1915, Vol. XXIII., p. 181. 



2 McCollum, E. v., Simmonds, E. V., and Pitz, W.: The Relation of the Unidentified Dietary 

 Factors, the Fat-soluble A and Water-soluble B, of the Diet to the Growth-promoting Properties 

 of Milk. Jour, of Biol. Chem., 1916, Vol. XXVII., No. 1, p. 33. 



3 Osborne, T. B., and Mendel, L. B.: Milk as a Source of Water-soluble Vitamine. Jour, of 

 Biol. Chem., 1918, Vol. XXXIV., No. 3, p. 537. 



« Hopkins, F. G., and Neville, A.: A Note concerning the Influence of Diets upon Growth. 

 Biochem. Jour., 1913. Vol. VII., p. 97. 



