CEEAM RAISED BY GEAVITY PBOCESSES. 173 



a large number of infectious bacteria do not thrive in a 

 substratum containing large quantities of lactic acid. 



Bacteria in Shallow-setting Cream. Proceeding to a 

 statement of the bacteria which my analyses of cream pre- 

 pared according to the shallow-setting method have shown 

 present, we first note that this cream when left on the 

 skim-milk shows a downy surf ace, especially when near the 

 ripening stage. This down comes from a growth of the 

 milk-molds (Oidium lactis) spoken of before. The part 

 which the molds play may be manifold : by their alkaline 

 reaction they may be the cause of the lactic-acid bac- 

 teria thriving and living for a somewhat longer time in 

 the sour cream. These molds also consume the acid in 

 the upper layer of the cream, thus causing a weakening of 

 acid in the lower layers of the milk, through which these 

 become better adapted to the anaerobic bacteria. Investi- 

 gations made after the first part of the original of this 

 work was written show that if we want to study the 

 anaerobic bacteria of the milk we may conveniently seek 

 them in just such milk-pans overgrown with molds. 



Those milk fungi furthermore appear to protect the 

 milk from later and possibly more dangerous infection. 

 They grow fast and spread, especially in tjie upper layers; 

 and. if they were not there, more dangerous micro-organ- 

 isms would most likely take their place. 



Excepting the molds mentioned, I have not, in spite of 

 numerous bacteriological analyses, been able to discover 

 any micro-organisms characteristic of this cream. The 

 bacteria found, both those infecting the milk as well as 

 the useful and desirable lactic-acid bacteria, are mainly 

 the same as those found in any other cream allowed to 

 sour spontaneously. A couple of points are, however, 



