58 INFECTIONS OF THE DIGESTIVE TRACT 



tract, and into the meconium on which they are able to 

 live, although it is only a fair culture medium. The 

 meconium thus contains forms which are the forerunners 

 of the permanent intestinal bacteria. In the case of 

 B. aerogenes capsulatus, it appears to me that its presence 

 in the meconium can hardly be explained on the ground 

 of its possessing motility, since it is questionable whether 

 this organism is ever at all motile, and certain that as a 

 rule it is non-motile. It is possible that it may be found 

 in the meconium in extremely small numbers as a result 

 of contamination at the time of the passage of the meco- 

 nium, since B. aerogenes capsulatus is so widely distributed 

 and so common an inhabitant of the air. Possibly, also, 

 the same explanation would apply to the presence of B. 

 putrificus, a spore-bearing organism which is common in 

 dust. 



We see thus that while non-motile forms of organisms 

 like B. lactis aerogenes, B. acidophilus, staphylococci, and 

 streptococci can find their way into the intestinal tract 

 only by way of the mouth, through the milk (being un- 

 endowed with motility), the members of the colon 

 bacillus group may invade the digestive tract either 

 through the mouth or the anus, and, finally, that B. 

 bifidus, the chief obligate bacterium of the milk-stools 

 of nurslings and a regular and permanent inhabitant of 

 the meconium, reaches the intestinal tract only by way 

 of the anus. It is noticeable that the meconium contains 

 a considerable proportion of spore-forming bacteria; 

 that is, of bacteria capable of resisting unfavorable in- 

 fluences. Whether they find their way into the intes- 



