INFECTIONS OF THE DIGESTIVE TRACT 59 



tine as spores or in their vegetative form is not clear 

 and is probably not important. They do, however, 

 sporulate in the meconium, which may perhaps be inter- 

 preted as indicating that the meconium is a poor rather 

 than a good nutrient medium for these organisms, al- 

 though I do not feel sure that this interpretation is 

 absolutely safe. It appears that the meconium is in 

 general a poor medium for bacteria, and this fact ex- 

 plains satisfactorily its relative poverty in bacteria. 

 The poor nutrient character of the meconium may be 

 due in part to its inspissation and in part to its relatively 

 high content of bile acids, which would tend to prevent 

 the rapid multiplication of invading organisms. It is 

 doubtless true that the meconium, in consequence of 

 these properties, exercises a selective action on the in- 

 vaders of the lower intestine, discouraging all those 

 vegetative forms that are non-resistant either through 

 the inability to adapt themselves to the peculiar con- 

 ditions of the medium or through the inability to form 

 spores. The meconium is therefore to be regarded as 

 possessing physiological functions instead of being an 

 indifferent substance. The main physiological function 

 of this meconial plug is apparently the exclusion of 

 numerous foreign types of bacteria and the encourage- 

 ment of those organisms which are destined to become 

 the permanent inhabitants of the nursling's digestive 

 tract. 



Bacterial Flora of Bottle-fed Children. If one makes 

 a comparison of the bacteria of the digestive tract of 

 children fed on cow's milk with the flora which has 



