Reductase Test. 217 



lias not been cooled, and has been transported in poorly cleaned 

 cans, ages more rapidly than milk which has been properly treated. 



In making the test it is not necessary to cover the sample in 

 the reagent glass with boiled oil or kerosene since there is no 

 advantage in such a procedure. In the same way the "reductase" 

 which is recommended by commercial firms is of no advantage. 



Fresh milk from individual cows may be rapidly reduced 

 owing to the large content of cells. 



Very valuable results are obtained with the reductase test 

 when conducted in connection with the microscopic examination of 

 the sediment. 



Frequently, in the testing of the centrifugal sediment, large 

 numbers of bacteria are found not infrequently agglutinated in 

 colonies, and the milk, in spite of the apparently high content of 

 bacteria, has very little reducing power. This is an indication 

 that the milk has been transported in uncleaned cans, but does 

 not in itself prove decomposition. 



Microscopically in the residue of milk in the can are found 

 milk souring bacteria, diplococci, streptococci, sarcines, besides 

 oidia, coli, and rods. 



Such is also the case when the milk is obtained under dirty con- 

 ditions, but is promptly delivered. 



The author determines the reduction property of the milk in 

 the following manner : 



For each sample of milk 10 small tubes are used containing 

 1, 2, 3, 4, up to 10 drops of methylene blue solution, respectively. 

 Into each tube 5 c. c. of milk is added. After 14, %, 1, 2 hours, 

 etc., observations are made as to what extent the milk has been 

 reduced. This method, in spite of its apparently greater technique 

 is nevertheless quite simple, as the constant watching of the sam- 

 ples in order to determine the time is unnecessary. Both time and 

 degree are determined. If, for instance, a milk is reduced in three 

 hours to tube 8, then the formula will be: R3 8. Good milk 

 reduces the first 2 tubes only after 2 to 3 hours; fresh milk only 

 after 10 to 12 hours. 



The Schardinger reduction of formalin methylene blue is of 

 no value for the examination of market milk, as it also gives posi- 

 tive results with fresh, raw, and boiled spoiled milk. In the same 

 way it is not suited for examination of milk from individual cows. 

 Milk, which does not decolorize in a few minutes at 60 C. by the 

 Schardinger reagent, consisting of 190 parts water, 5 parts forma- 

 lin and 5 parts saturated alcoholic methylene blue solution, may 

 be from fresh cows, if the individual sample is taken from the total 

 amount of milk of the cow (the first portion of milk at the milking 

 does not reduce). 



The "Catalase" test is conducted by mixing together 15 

 c. c. of milk and 5 c. c. of \% peroxide of hydrogen. The mixture 

 is placed in a fermentation tube such as is used in the examination 



