Germicidal Properties. 



Trommsdorff and Rullmann conclude from these and other experiments that the 

 bacterial content of milk does not increase at room temperature in the first period 

 following the milking. "On the contrary in some of the samples inside of the first 

 5 to 7 hours a pronounced diminution of the bacterial number was observed, which was 

 still more pronounced in the following period so that in a great number of cases the 

 bacterial number, after 1, 2, and even 3, and in one case even after 5 days, was found 

 lower than directly after the milking. Where there occurred no diminution in bacteria 

 the bacterial content remained the same as that found after the milking, during 1 to 3 

 days. ' ' 



Milk which has been contaminated with numerous bacteria 

 in the earliest periods after milking (dirty milking, filthy ves- 

 sels), shows only to a very slight extent the germicidal phase. At 

 37 deg. C. the germicidal substances act more rapidly, but the dura- 

 tion of the germicidal phase is shortened (Koning, Eullmann and 

 Trommsdorff). 



Heating the milk to over 70 deg. C. destroys its germicidal 

 properties. 



Bauer and Sassenhagen established the absence of complement in ripe milk which 

 gives the impression that in ripe milk the action is elective in the sense that the contained 

 substances constitute food for one microbe and poison for another. Of course, it has 

 been established for even ordinary kinds of bouillon that, depending on their composition, 

 the growth of certain bacterial species upon them has been checked for a time (Basenau). 

 The lecithin contents of raw milk must not be left out of consideration; in certain 

 concentrations lecithin exerts a strong inhibitory action on bacterial growth. 



Finally the diminution of the bacterial content may be only apparent, as the 

 bacteria may multiply through their sticking together in agglutinated masses, thereby 

 simulating a diminution, a view which is supported also by Bab for colostral milk. 



After the germicidal action of the milk has worn off the 

 various phases of decomposition of milk set in, beginning sooner 

 or later, depending on the original contamination of the milk. 

 Koning distinguishes seven such phases. 



The fight of the microbes, their harmonious, or again anta- 

 gonistic relation to each other, results in a predominance of cer- 

 tain species of bacteria in the various phases. 



First (second phase according to Koning, the first being the 

 germicidal) the proteolytes split up the proteid bodies of the milk, 

 and thereby prepare the soil for the acid producers, which domi- 

 nate the further decomposing phase (third phase according to 

 Koning) ; the milk coagulates. In the fourth phase the alkali pro- 

 ducers partly neutralize the acid again by further splitting up the 

 albumoses of the acid milk with the formation of ammonia. Pep- 

 tonized casein is also attacked. The principal representative of 

 this decomposing phase is the Bacillus fcecalis alkaligenes (Gram 

 negative, no gas formation, no indol, no spores, colors litmus milk 

 blue). Through neutralization of the lactic acid, certain lactic acid 

 bacteria, Bacillus acidi paralactici, Bacillus acidi Ifsvolactici and 

 Micrococcus acidi paralactici liquefaciens, again regain predomi- 

 nance (fifth phase). 



Up to this stage the higher fungi have played a subordinate 

 part, although they may have multiplied ; now they appear in great 

 masses. The degree of acidity does not hinder their growth. The 

 11 



