SUMMARY OF CHAPTER VI 



ON THE SO-CALLED ' BIOLOGICAL PROPERTIES ' OF MILK (continued) 



B. THE SUBSTANCES CONCERNED IN THE PRODUCTION 

 OF IMMUNITY 



THE subject-matter of this chapter forms the basis of one of the 

 most interesting, but at the same time one of the most difficult, 

 phases in the hygienic aspect of the milk question. 



The transference of immunity from one generation to another 

 has been the subject of investigation for a number of years, in fact 

 ever since the problem of immunity began to be studied. The 

 first phase in the investigations was directed towards ascertaining, 

 if possible, whether such immunity as might be found to be con- 

 ferred was conferred before or after birth. In the present work 

 the condition of the fcetus as regards immunity is only indirectly 

 of importance, since it evidently has no relation to milk. 



The early investigators studied the inheritance of immunity 

 from three possible points of view : (i) Through the father, (2) 

 through the mother before birth, and (3) through suckling. As a 

 result of these investigations it appears that no immunity is conferred 

 by the father, while there is some divergence of opinion in regard 

 to the possible conferring of immunity through the mother before 

 birth, the bulk of the evidence being definitely against this occur- 

 rence. The third line of investigation is the one with which this 

 present work is chiefly concerned. 



The production of immunity in any organism is not a simple 

 matter, but involves many complex considerations. Everyone is 

 aware that certain diseases once contracted by an individual confer 

 immunity from further attacks. Moreover, the difference in the 

 tendency to contract diseases between different individuals is a 

 matter of common knowledge. Some species of animals are more 

 liable to certain diseases than are other species, while others again 

 are entirely immune from diseases to which further varieties of 

 animals fall a ready prey. 



A very great amount of work has been carried out in order to 

 discover what mechanisms are at work in the animal organism, which 

 account for these remarkable phenomena. Although these in- 



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