690 ARTHUR ISAAC KENDALL 



D. Intestinal Bacteriology 

 General History and Development 



The earliest convincing studies of the hacteria of the alimentary canal 

 were those of Theodore Escherich upon the intestinal flora of nurslings. 

 This talented observer isolated and described many of the more common 

 and important normal microbes of the intestinal tract, inventing methods 

 for their recognition which are in use in modified form to-day. He tried 

 to correlate their physiological processes with normal and abnormal intes- 

 tinal conditions, as well. This work is of special merit, not only for its 

 detailed information, but also for the broad "viewpoint from which the 

 work was conducted. 



Comparatively little attention was paid to the work of Escherich for 

 several years after its publication. The discovery of the cholera vibrio 

 by Koch, in 1883, followed by that of the typhoid bacillus by Gaffky in 

 1884, focussed attention upon the disease-producing intestinal bacteria to 

 the virtual exclusion of the normal organisms and their relations. What- 

 ever progress was made in the study of the non-pathogenic types was 

 directly associated with methods for their detection and differentiation 

 from the pathogenic microbes. Intestinal bacteriology, in common with 

 the entire field of microbiology, became a purely diagnostic science. This 

 extensive interest in diagnostic intestinal bacteriology has been extremely 

 fruitful, however. The microbes which are causative agents in practically 

 all the acute intestinal infections of exogenous origin are now well known, 

 and the domain of preventive medicine has profited greatly through the ac- 

 cumulated information relating to the cycles of infection of these 

 bacteria. 



Escherich was unable to isolate the predominating organisms of the 

 normal nursling feces, although he recognized them morphologically and 

 realized that he was unsuccessful in this direction. It remained for 

 Tissier to accomplish this difficult task, and with his studies of Bacillus 

 bifidus commimis, the way was cleared for satisfactory studies of the in- 

 testinal bacteria from birth to adult iiie. 



The discovery of paratyphoid bacilli by Salmon and Smith, Gartner, 

 and Brion and Kayser, and their significance by Achard and Bensaude, 

 and of the dysentery bacilli by Shiga and Flexner, practically com- 

 pleted the list of bacilli which induce extensive epidemic intestinal disease 

 in man. 



Attention was then of necessity directed to the endogenous intestinal 

 organisms. Advances were made in two principal directions the isolation 

 of bacteria from the normal intestinal contents and their identification, 

 and, secondly, the study of intestinal microbes at different periods of 



