40 INFECTIONS OF THE DIGESTIVE TRACT 



it was naturally assumed that the main bacteria of the 

 large intestine of the nursling must be organisms of this 

 group (as in the case of bottle-fed children), the failure 

 of the nursling's fields to conform to this assumption at 

 once threw doubt on the view that the nursling's domi- 

 nant fsecal bacteria are really colon bacilli. The view 

 was put forward that the Gram-positive character of 

 the fields is due to the influence of the large fat content 

 of the mother's milk, 1 but this had soon to be abandoned. 

 It was only through the use of suitable cultural methods 

 that the mystery was solved. 



If one inoculates agar, gelatin, or bouillon media with 

 the mixed flora got from a healthy nursling and cultivates 

 the microorganism in the presence of air, bacteria of the 

 B. coli type show themselves regularly to be the dominant 

 forms, although they may be associated with diplococci, 

 and sufficiently refined methods give evidence of the 

 presence of the closely allied B. lactis aerogenes. If, 

 however, one grows the mixed flora on a suitably pre- 

 pared acid medium, 2 it becomes easy to restrict or even 

 quite check the growth of the members of the B. coli 

 group and to demonstrate the presence of a type of 

 microorganisms which grows readily in this acid medium, 

 has a morphology like that of the slender bacillary colon 

 forms, coagulates cow's milk but does not act on human 

 milk, and is definitely Gram-positive. This micro- 

 organism, or rather group of microorganisms, accounts 



1 Alex. Schmidt, "Zur Kenntniss der Bakterien der Sauglings- 

 faeces," Wien. klin. Wochenschr., v, p. 643, 1892. 



2 Acid beerwort or acetic-acid bouillon, as suggested by Moro. 



