CLARIFICATION OF MILK. 241 



IV. SUMMARY. 



1. It is evident that our present knowledge of clarification does not 

 enable us to reach a scientific interpretation. 



2. An intimate study of clarification not only reveals facts which assist 

 in its understanding, but also leads us into depths beyond our reach. It 

 is constantly presenting suggestions concerning milk investigations which 

 have not been considered heretofore through established channels. A 

 fertile field for research is opened. 



3. The slime eliminated and the comparison of the clarified milk with 

 the unclarified seem to offer, at the present time, the best approach to 

 the study of clarification. 



4. The amount of slime eliminated from milk is variable, and dependent 

 upon — 



The condition of the cow, whether normal or abnormal. 



The period of lactation. 



The age or freshness of the milk. 



The acidity of the milk. 



The temperature at the time of clarifying. 



The amount of corpuscular elements. 



The amount of insoluble dirt in the milk. 



5. The food value removed from milk through the elimination of slime 

 may be disregarded, unless there are contained within some of the ele- 

 ments of the slime nutritional activators, as the so-called vitamines, 

 which seems improbable. 



6. Masses of cells are thrown out in the slime. This is especially em- 

 phasized when any inflammation exists in the udder. Garget, existing as 

 it does in ropy, tenacious form, is completely ejected. What significance 

 is to be attached to normal cells, so far as the authors are concerned, 

 cannot be stated from our present knowledge. 



7. A fibrinous material responding to fibrin stains is practically wholly 

 eliminated from milk in clarification. 



8. Practically all insoluble dirt is removed in clarification. The clari- 

 fier is the most effective strainer employed in the diary. Its efficiency 

 in this respect is greater than that of the cotton filters of the Wisconsin 

 Sedimentation Tester. Dirt in solution, of course, is not subject to the 

 action of a centrifuge or clarifier, inasmuch as it diffuses throughout the 

 whole mass. 



9. Micro-organisms are found in large numbers — yes, in masses — in 

 the slime. These come from the milk, since there is no other source, and 

 there is not suflScient time to multiply while passing through the clarifier. 

 In certified milk there is also a reduction shown after clarification, as 

 revealed by the plating method. In market milk the number is usually 

 increased after clarification, as revealed by the plating method. This is 

 doubtless due to the disruption of colonies. Besides the above evidence 

 there are the results of repeated clarification of milk and pure cultures, 



