EXPERIMENT STATION BULLETINS. 



419 



PART I. 



DETERMINATION OF THE SIGNIFICANCE OF TUB ORGANISMS OTHER THAN 



LACTIC IN THE ORIGINAL CULTURE. 



Expt. I. 



Is the Yellow Coccus Existent in the Orijjinal Mixed Culture an Im- 

 portant or a Negligible Factor in the Retention of the Activity 

 of the Lactic Bacteria? 



In the effort to isolate the red organism from the original mixed 

 culture a yelloAv coccus was found in addition to the red yeast and the 

 lactic bacterium. This yeast, designated hereafter as LZ, was used in 

 combination with a well known lactic organism, a typical starter bac- 

 terium designated as Strain 2. for determining the relative importance 

 of the yellow coccus in the mixed culture. The coccus was isolated in 

 pure culture and transferred to milk and observed from time to time. 

 It produces acid and eventually curds milk producing a tough curd 

 which shrinks rapidly leaving the whey almost clear. 



In order to determine its importance in the mixed culture, the fol- 

 lowing inoculations were made using 1 cc. of a 3 weeks old culture of 

 No. 2, 1 cc. of a 53 day milk culture of the yellow coccus and 1 cc. of a 

 53 day whey culture of the yeast LZ. Duplicate cultures were made 

 each, of No. 2 plus the yellow coccus, yeast LZ plus the coccus. No. 2 

 plus the yeast, and the coccus, lactic bacterium and yeast combined. 

 These were titrated frequently and the changes in the milk noted. 



The coccus growing alone in whey and in milk gave the following re- 

 sults upon titration. 



TABLE'I. 

 Acid Production of Yellow Coccus. 



*Milk curded, whey separated. 



**Curd hard, not easily broken up by shaking. Low acidity most probably due to the necessarj' lack of homogenicity of the 

 ample used in titrating. 



TABLE II. 

 Effect of the Presence of the Yellow Coccus in the Original Culture. 



*Test cultures made at this time. See Table III, 



