60 INFECTIONS OF THE DIGESTIVE TRACT 



already been described as characteristic of the digestive 

 tract in breast-fed children, one finds many points of 

 resemblance but also some typical and important differ- 

 ences. In general it may be said that the number of 

 bacterial forms present in the digestive tract of children 

 nourished with cow's milk is considerably greater than 

 in the case of breast-fed children. This is true even 

 where children are fed^on cow's milk that has been 

 sterilized by boiling or by pasteurization. And the 

 difference in number is even greater in those cases where 

 sterilization has not been practiced, since this procedure 

 destroys a large proportion of the bacteria present in 

 the milk and especially the lactic acid producers. Where 

 sterilized milk is employed the increase in the number of 

 bacteria in the digestive tract as compared with the 

 number of varieties present in the intestines of breast- 

 fed children is dependent at least in part upon the 

 presence of anaerobic bacteria or facultative varieties 

 capable of forming spores. 



That the number of bacteria should ordinarily be 

 greater in children fed on cow's milk than in children 

 fed on mother's milk can cause no surprise, when one 

 remembers how abundant are the microorganisms present 

 in most specimens of cow's milk. The number ordi- 

 narily ranges from one or two thousand bacteria per cubic 

 centimeter * in cow's milk that has been collected with 

 the utmost precautions in regard to cleanliness"of pres- 

 ervation, up to several million per cubic centimeter. 



1 Under very special conditions milk can be obtained which has 

 a far smaller number of bacteria. 



