874 EXPERIMENT STATION RECORD. 



Tlio results olitiiiniHl fioni a study <»t" individual chooses duriiifj vipeniufr are 

 prosoutod in tabular form. " In difforout chooses the rate of increase, the niaxi- 

 luuin jierni content, and tlie ajio at which it is obtained, as well as the rate of 

 doclino after this point, varied greatly. The causes of these variations are 

 only partly understood. . . . Tlie lowest recorded maximum, 27,000,000, and the 

 hifihost. 178,0()0,(KX) per gram are in the 2 cheeses having a very similar 

 qualitative flora and ripening in a similar manner. The rate of ripening in 

 these 2 cheeses was slightly different, the one with the highest maximum 

 germ content ripening more slowly." The average germ' content of all the cheese 

 examined was 10,000.000 per gram at the end of 5 hours, 30.000.000 at the end 

 of 1 day, 40,700,0(X) at the end of 10 days, 10,200,000 at the end of 50 days, 

 2,025,000 at the end of 100 days, and 500,000 at the end of 15(J days. 



" The type D. lacti.s acidi makes up 09 per cent or more of the flora of normal 

 Cheddar cheese in practically all cases. The representatives of this type differ 

 in their relation to air and in their ability to attack saccharose, so that they are 

 found under 4 different group numbers. . . . Streptococcus lacticiis, which in- 

 cludes 2 different group numbers, is occasionally found in much smaller num- 

 bers. These groups apparently agree with the corresponding groups of 13. lactis 

 acidi in everything except morphology. The position taken by Conn, that there 

 is a distinct morphological basis for the separation of the cocci from the rod 

 forms, api)ears to be well taken. Both the morphology and the physiology of 

 these groups is easily influenced by their environment, and it is especially 

 important that the cultures be brought to a vigorous condition before being 

 subjected to detailed study. 



" The acid liquefiers which are considered so important by Gorrini are repre- 

 sented by Micrococcus lactis albidus (2 groups), M. lactis gigantcus, M. lactis 

 rariaiis (4 groups), and 31. lactis brcvis. M. lactis albidus and 21. lactis brevis 

 occurred sufficiently often to suggest that they might play some part in the 

 ripening changes. Representatives of this group were found in all but [one 

 cheese]. These forms grew well in the milk but made little headway in the 

 cheese, although they survived there better than the nonacid-producing forms. 

 Their number as compared to the total germ content of the cheese, was rela- 

 tively insignificant. 



" The gas-producing forms, like the preceding group, find the best conditions 

 for their development in the milk and make little or no growth in the cheese. 

 Bacillus coli ucrogencs was found in the milk [for 2 cheeses]. In both cases 

 it was not found in the cheese after the first day. The isolated cultures were 

 slow gas producers and did not displace more than one-third of the closed arm 

 in the fermentation tube. 



"Bacterium lactis aerogcncs was found in [4 cheeses. When present in 

 considerable numbers] evidence of gas was noted in the vat during the early 

 stages of the making process. These forms are very resistant to the acidity 

 in the milk and cheese, but our data do not show that they multiply in the 

 latter. 



" The inert group, characterized by a lack of any apparent action upon milk, 

 is represented by Galactococcus versicolor and B. lactis connii. They are fairly 

 numerous at times in the milk and fresh curd. They usually disappear quickly. 

 There is no evidence that they increase in the cheese. 



" Very few specimens of yeasts have been found, although an effort was made 

 to prepare plates especially suitable to their habits of growth. . . . 



" The system of i-ecording the reactions of cultures as proposed by the Society 

 of American Bacteriologists is a marked advance in technique. By its aid the 

 shifts in tlie cheese flora can be followed with more accuracy than was previ- 

 ously possible. The cultures isolated can readily be so characterized as to be 



