TRANSMISSION OF TOXINS THROUGH MILK 243 



through the intestinal mucosa of the young mammal into the 

 circulation. 



Most of the studies on transmission of antibodies through milk 

 have been carried on with antitoxins.. However, some evidence 

 is at hand which seems to indicate that other immune bodies may 

 be transmitted through milk directly to the suckUng. Trans- 

 mission of agglutinins, bactericidal substances, hemolysins, and 

 opsonins (Woodhead and Mitchell) have been observed, and 

 even hypersensitiveness seems to be transmissible through milk. 



Agglutinins have been observed in the circulation of the fetus 

 and in the milk of immunized mothers. Typhoid fever agglutinins 

 especially have been shown to exist in the milk of women suf- 

 fering or recovering from typhoid fever. 



Experiments as to the transmission of agglutinins through 

 milk to the young have not always led to concordant results. 

 While some observers claim that this is possible, even though the 

 quantity transmitted is small, others were unable to detect the 

 presence of agglutinins in the circulation of the young. 



Precipitins have been found in the blood of sucklings, and 

 their presence is due to the passage of proteins through the in- 

 testinal wall. Whole milk and the different milk proteins sepa- 

 rately can act as antigens. Injection of milk into animals produces 

 specific antibodies and a serum containing these antibodies is 

 called lacto-serum. In infancy, when milk proteins pass through 

 the intestinal wall, or in cases where the intestinal mucosa is in- 

 jured so that proteins can pass through, precipitins are formed in 

 the blood. The presence of precipitins is demonstrated by add- 

 ing some of the serum to a solution of the particular protein which 

 has induced antibody formation. For example, an animal treated 

 with cow's milk will produce precipitins which react only with 

 cow's milk; or if bovine casein is injected, the blood-serum of the 

 animal will develop precipitins to bovine casein and not to casein 

 of another kind of milk. It is possible by means of the precipitin 

 reaction to detect adulteration of one kind of milk with that of 

 another mammal. If, for example, goat's milk has been mixed 

 with cow's milk, this can easily be detected. Milk from one 

 mammal, if heated to the boihng-point, can still be distinguished 

 from milk of another species by this biologic test. Even if de- 

 composed, as in ripened cheese, the kind of milk used can be 

 determined. However, the specificity of the reaction is not 

 strictly confined to the milk of the same species, as milk from 

 closely related species will react, although in lesser degree. 



Precipitins, like agglutinins, belong to the second order of 

 immunity, according to Ehrlich's hypothesis. 



Hemolysins and bactericidal substances belong to the third 



