SO-CALLED 'BIOLOGICAL PROPERTIES' OF MILK in 



when the antitoxin has been received through the mother. This 

 is attributed to the nature of the protein to which the antitoxin 

 is attached. When it is added directly to the milk it will probably 

 be attached to a protein which is ' foreign ' to the suckling animal 

 under investigation. It appears that although some absorption 

 of ' foreign ' protein does occur, it is absorbed in smaller amount 

 than the ' native ' protein of the mother's milk. 



Direct absorption of protein does not occur later than the first 

 few days after birth, except in some cases where the condition of 

 the alimentary canal is abnormal. This may be the case in general 

 disturbances, and can also be induced artificially. 



Many of the investigations upon the transference of immunity 

 by means of suckling have been carried out with antitoxin, with 

 the results which have just been mentioned. Experiments have 

 also been carried out in order to determine the occurrence in milk 

 of those bodies normally present in the blood of adult animals, 

 which are concerned with the production of immunity. 



The factors concerned in haemolysis have been found to be 

 present in colostrum. One of these (amboceptor) is only found 

 in the first two to three days, the other (complement) persists for 

 a few days longer. Some authors have found evidence of the 

 presence of this factor in later milk. There is a good deal of 

 evidence tending to show that the reaction used to demonstrate the 

 presence of complement depends upon other factors. 



There has been a good deal of discussion upon the power of 

 milk to destroy bacteria. Some observers have even regarded it 

 as a sufficient protection against infection through milk. These 

 claims can in no way be substantiated as a result of investigations 

 and as further evidenced by the occurrence of epidemics, which 

 have been traced indubitably to milk. A decrease in the number 

 of colonies of bacteria found, on plating out milk, has undoubtedly 

 been shown to occur after milking. After a few hours, however, 

 this phenomenon is not exhibited, and even when it has occurred 

 in the early hours the number of colonies at the end of twenty- 

 eight hours does not suggest any permanent decrease in the number 

 of bacteria. It appears probable that the diminution in colonies 

 is due to the agglutination or clumping together of several bacteria, 

 which, as the agglutinating power wears off, again separate and 

 begin to multiply vigorously. 



Our knowledge upon the transference of immunity by suckling 

 demonstrates the immense value to the young of the colostrum 

 of its mother, and emphasises the need for breast-feeding. 



