INFECTIONS OF THE DIGESTIVE TRACT 61 



Although the character of the bacteria is much more 

 important than their number, those specimens of milk 

 which contain the largest numbers are also most likely 

 to contain the forms which, aside from the inciters of 

 typhoid fever and dysentery, are most injurious; that 

 is, especially, the streptococci and the putrefactive anae- 

 robes. Ordinarily good milk frequently contains from 

 thirty to one hundred thousand bacteria per cubic cen- 

 timeter. Thus we see that there is good reason why the 

 mouth and stomach are liable to contain much larger 

 numbers of bacteria in the case of children fed on cow's 

 milk than in the case of breast-fed children, and it is 

 further clear that the actual number will vary somewhat 

 with the character of the milk that is employed. As in 

 the case of breast-fed children, there is a marked dimi- 

 nution in the number of bacteria found in the upper part 

 of the small intestine as compared with the bacteria in 

 the stomach. This diminution, which probably de- 

 pends in part on the bactericidal action of the gastric 

 juice and intestinal juices, tends to bring about in the 

 small intestine a greater equality in the number of bac- 

 teria in breast-fed and bottle-fed children than is ob- 

 served at higher levels. Nevertheless, even in the lower 

 part of the small intestine and throughout the large 

 intestine, the number of bacterial species appears to be 

 as a rule greater in the case of children fed on cow's milk 

 than in the case of nurslings. 



Many of the bacterial forms which have already been 

 described as regular inhabitants of the nursling's intes- 

 tinal tract are also inhabitants of the digestive tract of 



