186 Reductase, Catalase, Etc. 



2 J /4 hr. after 12 hrs. at 25 deg had an acidity of 15 



3% hr. after 12 hrs. at 25 deg. had an acidity of 9 



6*4 hr. after 12 hrs. at 25 deg. had an acidity of 9 



7 hr. after 12 hrs. at 25 deg. had an acidity of 10.5 



6y 2 hr. after 12 hrs. at 25 deg. had an acidity of 8 



7% hr. after 12 hrs. at 25 deg. had an acidity of 8 



12% hr. after 12 hrs. at 25 deg. had an acidity of 7 



8y 2 hr. after 12 hrs. at 25 deg. had an acidity of 7.5 



The findings of the author were very much the same as those of Jensen. 

 Milk which failed to reduce in 20 hours had after 24 hours at 20 deg., from 7.4 to 

 10 degrees of acidity. 



The following table shows the results of the technique em- 

 ployed in testing milk, where the reduction number is understood 

 to mean the number of drops of methylene blue solution which in 

 a given time was completely reduced by 5 c. c. of milk: 



Degree of acidity After 24 hrs. Time required 



at delivery at 20 deg. for reduction Reduction number 



7.0 7.4 20 hrs. 



6.2 8.6 20 hrs. 



6 10 20 hrs. 



6 9 20 hrs. 4 



7 10 20 hrs. 

 6 24 4 hrs. 2 



6.4 26.5 8 hrs. 10 



6.5 26 8 hrs. 6 

 6.2 24 8 hrs. 8 

 6.2 27 8 hrs. 6 

 6.8 23 8 hrs. 4 

 6 14 8 hrs. 4 

 7.8 30 6 hrs. 4 

 6.5 28 2 hrs. 2 

 7.2 32 Ihr. 2 

 6 34 Ihr. 2 

 6.2 38 Ihr. 10 



8 40 5 hrs.' 10 

 10.5 26.4 0.5 hrs. 10 



6 30 6 hrs. 2 



These numbers were obtained from a great number of sam- 

 ples during work at the milk control station, without any selec- 

 tion. They show that milk which sours rapidly, and is therefore 

 at the end of the incubation period, also reduces rapidly; there 

 exists, however, no absolute constancy in the parallelism, neither 

 with the values of acidity in milk after twelve to twenty-four 

 hours, nor with the values in samples of fresh milk. 



After thorough souring the reduction power of the milk again 

 diminishes for a time. This may be due to the fact that the acid 

 reaction inhibits the reduction power as a matter of fact the 

 rapidity of reduction is again considerably increased by the addi- 

 tion of sodium carbonate or bicarbonate and also because a non- 

 reducing organism, the acid streptococcus, outgrows the other 

 bacteria. 



The addition of an alkaline solution brings about acceleration 

 of the reaction only in sour milk, while in milk with low bacterial 

 count the reaction is retarded, but this may be overcome when 

 through acid formation neutralization has taken place. 



