276 FERMENTATIONS IN MILK 



Adametz, a variety which renders milk slimy and causes 

 trouble in dairies sometimes. 



(c) Group iii. In this group the typical form may 

 be taken as Bacterium casei, Freudenreich. The 

 organism is a thin, elongated rod, 2 to 3 ^, long and 

 5 to .7 /x broad. Most of the forms in this group grow 

 feebly and are usually more or less anaerobic. Their 

 colonies are small, about the size of a pin's head, white 

 or yellowish-white, and variable in. shape. The typical 

 Bact. casei produces inactive lactic acid in milk and 

 coagulates the latter in three, days at a temperature of 

 30 C. with gas formation. Allied to it are Bact. 

 casei, Leichmann, and Bact. lactis acidi, Marpmann, which 

 do not produce gas in milk. Bs. caucasicus, Beijk. 

 (p. 315), one of the active fermentation agents in Kefir 

 grains, and/).?, bulgaricus, Heupel.(p. 3 19), should probably 

 be included in this group. Other allied forms are known 

 which neither precipitate casein nor form gas. 



(d) Group iv. The type species or form of this 

 group is Micrococcus lactis acidi, Marpmann. It is a- 

 small coccus .6 to .8 ^ in diameter, occurring singly or 

 in pairs and small heaps, but never in chains. In milk 

 it grows slowly, rendering it acid at 20 C., but not 

 coagulating it below 30 C. The colonies on gelatine 

 are small and round, yellowish-white in colour, growing 

 chiefly on the surface of the plate. No gas is formed. 

 Micrococcus pyogenes, Rosenbach, and its varieties, which 

 are associated with the formation of pus in various 

 inflammatory and suppurative diseases, belong to this 

 group. They coagulate milk and tend to produce 

 enzymes, which dissolve casein and liquefy gelatine. In 

 some varieties the colonies are white, in others different 

 shades of yellow or orange. The organisms producing 



