BACTERIA COMMONLY FOUND Itf COWS* MILK. 107 



the relation of a large number of different yeasts in this 

 respect, and found that only two of them may be consid- 

 ered as enemies of the quality of the milk. These produce 

 lactic-acid fermentations, and also form alcohol in it in 

 smallef or larger quantities. In " Saprophytic Micro-or- 

 ganisms in Cows' Milk/' pp. 34-36, 1 have characterized 

 more fully these two organisms, which I have named Sac- 

 charomyces lactis and 8. acidi lactici. 



The latter yeast has several times been found by me in 

 Finnish milk, both in milk from the Kuopio and the 

 Joensum region, and in samples coining from Borgaa. 



Besides bacteria and yeasts, molds often appear in milk. 

 We see mentioned in many text-books that the milk has 

 a special mold, Oidium lactis. As a matter of fact, how- 

 ever, we very often find organisms in the milk which long 

 have had this name in bacterial science; they are especially 

 found in milk left to sour in wooden pans. Every sample 

 of sour milk of this kind which I have met with has been 

 strongly infected by oidium lactis. The fact seems to be, 

 however, that several different moulds hide themselves 

 under this name, and that oidium lactis only signifies a 

 certain stage of development with different moulds a stage 

 when they all have about the same appearance. They ap- 

 pear to the naked eye as a fine, white, velvet down on the 

 milk; under the microscope they appear like ramified 

 threads separated by numerous cross walls. We shall in a 

 later chapter return to the action of these moulds in the 



k - 



