TRANSMISSION OF TOXINS THROUGH MILK 241 



Toxins are produced by some animals (snake venom, spider 

 poison), plants (abrin, ricin, crotin), and by some bacteria. Bac- 

 terial and animal poisons are usually harmless to adults when 

 taken through the alimentary tract, but may not be harmless in 

 the infant's digestive tract. Most toxins, when introduced into 

 the digestive tract, are decomposed by digestive ferments and 

 rendered harmless. The poison produced by the bacillus of 

 botulism is a notable exception to this rule. In the digestive tract 

 of infants there is no such digestion of toxins, and their intro- 

 duction may therefore be followed by grave consequences. How- 

 ever, the toxins — if present at all in the milk — are there in rela- 

 tively small quantities, and, furthermore, the mother is not able 

 to nurse her infant if she is suffering from a serious toxemia. 



Vegetable poisons exert their poisonous influence from the 

 alimentary tract, but probably rarely occur in milk, since the 

 plants from which they are derived are not common in pastures. 

 It has not been conclusively shown that vegetable poisons pass 

 through the normal mammary gland into the secretion. 



The transmission of antibodies with milk from the mother to 

 the young is of much interest and perhaps of value in regard to 

 the health of the infant. There is a popular impression that dur- 

 ing the first year of life infants are not highly susceptible to dis- 

 eases, such as scarlet fever, measles, whooping-cough, and typhoid 

 fever. This impression has been entertained chiefly in regard to 

 breast-fed infants. Whether the idea is in accord with facts has 

 not been proved, and it must be admitted that other factors may 

 cause this seeming immunity. For example, a young baby, as 

 a rule, is not exposed to infection to the same extent as older 

 children, as it does not come in as close contact with other children. 



The transmission of immune bodies to the young was thor- 

 oughly studied by Ehrlich. Previous to his experiments some 

 observations were recorded which showed that immunity was 

 present in the young, but whether it was communicated before 

 birth or afterward with the milk was not clear. By an ingenious 

 experiment Ehrlich was able to show that antitoxins actually pass 

 with the milk into the system of the suckling. He took young 

 mice born of a normal mother and had them fed by a mother that 

 had been actively immunized. The immunity of the foster 

 mother was transmitted to the young. When the mother was 

 passively immunized antitoxins were also transmitted through the 

 milk to the young. 



Ehrlich was able to show by experiment that — 



1. Immunity is not conferred from father to child. 



2. Immunity may be transferred before birth from mother to 

 child. 



16 



