THE BACTERIAL PROCESSES IN THE DIGEST- 

 IVE TRACT OF NORMAL NURSLINGS AND 

 BOTTLE-FED INFANTS 



Nursling Infants. In babies fed on mother's milk 

 the alimentary tract is the seat of conditions of bacterial 

 activity that possess a high degree of interest for one who 

 wishes to obtain an insight into the physiology of diges- 

 tion. For in nurslings one finds a relatively simple bac- 

 terial flora which gives a clew to the more complex and 

 puzzling bacterial conditions that characterize normal 

 adult life and many states of disease. The healthy 

 nursling's bacterial flora is not merely relatively simple 

 as regards the varieties of microorganisms; it is also 

 remarkably definite in the individual child during the 

 nursling period as well as in different children who are 

 nourished on mother's milk. 



By means of the Gram stain, carefully employed, it 

 is possible to divide all the bacteria present at a given 

 level into two groups, those which retain the stain and 

 thus appear dark blue in the microscopical field (Gram- 

 positive bacteria) and those which do not retain the 

 stain (Gram-negative bacteria), and are hence suscep- 

 tible to coloration by a counter-stain (a red dye such 

 as fuchsin or saffranin being usually chosen). As these 

 different ways of behaving to the stain correspond to 

 biochemical peculiarities of the bacteria, we have at our 



37 



