THE BACTERIA OF THE ALIMENTARY TRACT. 161 



active in inhibiting their growth and reproduction are prac- 

 tically not at all understood, it is riot strange that opinions 

 differ. 



1. That bacteria exist throughout the alimentary tract is 

 no longer doubted by any one. At what time do these bac- 

 teria appear? The majority of investigators are agreed that 

 under normal circumstances the alimentary traot of new-born 

 animals is, sterile. This condition of affairs does not last 

 long, however, for, as shown by the observations of POPOFF, 

 SCHILD, and ESCHERICH, the faeces of young children may con- 

 tain several kinds of bacteria as early as ten hours after birth, 

 and only rarely are they absent at the end of twenty-four. 

 BORDANO found even the colon bacillus thirteen hours after 

 birth. These bacteria enter the intestinal tract through 

 air, food , and bath-water by way of the mouth and rectum. 1 



2. In order to show the enormous number of bacteria 

 which inhabit the intestinal tract, the figures of SucKSDORFF 2 

 may be cited, who found in one milligram of normal human 

 faecal matter an average of 381,000 micro-organisms. Yet 

 the figures vary considerably, even within twenty-four hours, 

 between the extremes of 2,300,000 and 25,000 per milligram. 

 The variation in the number is, according to SUCKSDORFF, de- 

 termined chiefly by the kind of food, and but little by the total 

 amount of faeces or the amount of water contained in them. 

 When only sterile food is consumed, the average number of 

 bacteria per milligrap is markedly reduced. BROTzu 3 has 

 observed that this is true for the dog also when fed only 

 sterile food. From the total amount of faeces cast off and the 

 number of micro-organisms contained in each milligram, the 



1 See, for example, J. H. F. KOHLBRUGGE: Centralbl. f. Bakt., 1901, 

 XXX, lie Abth., p. 17; GERHARDT: Ergebnisse der Physiologic, 1904, 

 III Ite Abth., p. 107, where extensive references to the literature may 

 he found. 



2 SUCKSDORFF: Arch. f. Hyg., 1886. 



3 Quoted from KOHLBRUGGE: Centralbl. f. Bakt., 1901, XXX, He 

 Abth., p. 13. 



