SO-CALLED 'BIOLOGICAL PROPERTIES' OF MILK 119 



some extent the claims as to bactericidal power, but the effect 

 appears to have completely worn off at a later stage, when all 

 the samples to which B. Coli had been added gave a bacterial count 

 too high to estimate. 



The results could readily be interpreted as due to the 

 agglutinating power which is known to be present in fresh milk 

 and which has already been considered. 



The probability that it is the agglutination of the bacteria 

 which is one of the prime factors in producing the decrease in 

 bacteria during the early hours after milking, receives confirmatory 

 evidence from the investigations of those who have studied the 

 presence of agglutinins in milk. Thus Kraus (1901) found that 

 artificial agglutinins, if present in the blood, were passed out into 

 the milk. Langer showed that the agglutinating power of colos- 

 trum is greater than that of the later milk, and von Zubrzycki 

 and Wolfsgruber found that haemagglutinins were present in 

 colostrum, but that only traces could be detected later, the re- 

 action being most marked in the first two or three days. These 

 authors showed that the agglutinins were present for a longer 

 period in primiparous women than in multiparous. 



Tunnicliffe (1912) showed that the opsonic power of milk for 

 streptococci, staphylococci, and tubercle was greater in colostrum 

 than in later milk. The streptococcus phagocytic index for serum, 

 in one woman whose milk was investigated, was 0-8 in the serum 

 and o-i8 in the colostrum. 



The work upon the presence of bactericidal substances or 

 agglutinins in human milk and in colostrum is neither very extensive 

 nor are the results very convincing. Clinical evidence has been 

 obtained of the presence of agglutinins in the milk of women 

 suffering from typhoid fever. For further details of work compare 

 Honigmann, Moro (2, 4, 7), Cozzolino, Klimmer, Schenk, Noeggerath 

 and Kolff, Kleinschmidt. 



Summarising the question of bactericidal power possessed 

 by raw milk, it appears that there is some evidence of decrease 

 in the number of bacteria during the first few hours after milking, 

 as shown by the methods of plating out. It is not unlikely, 

 however, that this is apparent rather than real, and is due to the 

 agglutination of the bacteria by agglutinins present in the milk. 

 The inhibitory power which is present depends for its persistence 

 upon the temperature at which the milk is kept, but in ordinary 

 circumstances would not appear to last for more than twelve 

 hours after the milk has been drawn. As milk is seldom delivered 

 to the customer within twelve hours after milking, the bactericidal 

 power of milk from the point of view of infant hygiene may be 

 neglected. 



The presence in ordinary milk of factors concerned in haemolysis 

 is probably in itself a matter of comparatively little importance. 

 The same is almost certainly true of the bactericidal or agglutinating 



