i82 FERMENTATION IN MILK 



probably gains access to the milk by the cleansing of milk utensils 

 with water impregnated with the organism. 



3. Micrococcus Freudenreichii of Guillebeau. — A large aerobic 

 and facultative anaerobic coccus of 2 mm. or more in diameter, 

 described by Guillebeau as endowed with motility — often arranged 

 in small chains, especially in broth cultures. First isolated from a 

 milk factory at Berne, which had suffered much from ropy milk, 

 and recently held to be the cause of slimy milk in Switzerland. 

 Cultures on gelatine give a white growth, with rapid liquefaction 

 of the medium — colonies granular and punctiform. On agar the 

 colonies are white. On potato the growth is of sulphur yellow, 

 occasionally taking a brownish tint. Introduced into bouillon 

 it produces great turbidity, which gradually clears, a flocculent 

 precipitate forming at the bottom of the tube. In sterilised milk 

 the organism thrives best at a temperature of 20° C. The medium 

 becomes rapidly acid, and so stringy that threads of a yard or 

 more in length can be drawn out. If kept at 35° C, however, the 

 ropiness disappears after two days. There is no production of 

 gas, but old cultures of the organism develop a disagreeable odour. 

 The organism is killed at a temperature of 100^ C. in two minutes, 

 but bears desiccation well. 



4. Bacillus Hessii of Guillebeau} — An aerobic, actively motile, 

 non-capsulated, spore-bearing bacillus of from 3 to 5 mm. in 

 length by i to i-2 mm. in breadth. First isolated by Guillebeau 

 from ropy cream at Emmenthal in the Canton of Berne, Switzer- 

 land. It liquefies gelatine, and grows upon all the ordinary 

 media at room temperature. On gelatinised milk or nutrient 

 gelatine with an admixture of milk serum, there is a rapid appear- 

 ance of colonies with a well-defined border, which, however, dis- 

 appears as the liquefaction of the gelatine proceeds, the colonies 

 with their broken borders remaining suspended upon the liquid 

 surface. The liquefied gelatine is extremely viscous, and may be 

 drawn into threads. Cultivated upon potato, the organism gives 

 rise to a dirty white growth, turning later to a brownish hue. In- 

 troduced into bouillon, the medium becomes rapidly viscous and 

 of an alkaline reaction. In milk, however, the organism appears 

 to be soon crowded out by the lactic acid bacteria, when the 

 viscosity disappears. The resultant effect, therefore, cannot be 

 considered so serious as in the case of those organisms to which 

 allusion has already been made. 



5. Bacillus lactis piiuitosi. — A bacillus described by Loffler as 



1 Centralb.f. Bakt., xi. 439. 



