EXPERIMENT STATION BULLETINS. 



405 



ANAEROBIC ORGANISMS. 



Fifty-six cultures were isolated from the plates kept in Noyy jars under 

 anaerobic conditions. These were transferred from the isolation plates to 

 duplicate slant agar tubes, one of which, in each case was placed in an at- 

 mosphere of hydrogen while the other was left in the air. In no single in- 

 stance was an organism found which failed to grow well under serobic condi- 

 tions. No attempt was made to isolate anaerobic bacteria after the first 

 examination. 



THE ORGANISMS FROM WHEY AGAR. 



Duplicates of all plates made in the first examination were run in whey agar 

 made as described under methods. These plates had been expected to give 

 higher counts than the standard agar plates, but actually gave only half the 

 numbers, or even less for the ordinary lactic acid organisms. The other bac- 

 teria did not develop so well on these plates. So far as the lactic bacteria 

 are concerned, the results do not agree with some of tlie earlier work in this 

 laboratory and it is, therefore, being continued. 



LACTIC ACID BACTERIA. 



The table X gives the lactic bacteria in percentages of the total number 

 found in fresh butter. The averages of these show that the decrease is fairly 

 regular; in November we had still about 14-17% of the original number 

 alive; in February there were only 6% left. Though the averages agree very 

 nicely, in single samples there are often great variations; for instance, IV 

 and XXI with the extraordinary high numbers, and II, VIII and X with 

 their rapid decrease. 



The decrease of bacteria seems to be clearly connected with the amount 

 of salt, or rather, with the concentration of brine, in the butter. In arrang- 

 ing the samples according to the brine concentration in three groups we get 

 the following averages: 



The salt is certainly not the only reason for the decrease of bacteria, for 

 we have seen very striking exceptions: e. g., Sample XXI with a brine con- 

 centration of only 10.8%, but a very high percentage of lactics. 



The better keeping of bacteria in the high salted samples can be explained 

 in two different ways. Probably the low salted butter was frozen in the 

 cold storage and the bacteria could no longer multiply, but died slowly as 

 was found in ice-milk by Bischoff, whereas, in the high salted butter the 

 brine is not frozen and the bacteria have a chance for a very slow develop- 

 ment. 



It may be possible, however, that the brine surrounded by fat and dis- 

 tributed in small drops, does not solidify in the cold storages. The bacteria 

 of the low salted butters develop more rapidly and of course decrease earlier 



