Morphological Studies in the Life-Histories of Bacteria. 471 



results shown in the drawings and photographs of the selected strains. I 

 must be content, therefore, with stating that the essential results were the 

 same in all cases, approximately 1000 films having been examined. The 

 organisms which I have chosen in order to illustrate my points here are the 

 B. typhosus of Eberth, the B. dyscntcrice of Shiga-Kruse, the B. dysenterice T. 

 of Hiss, and a bacillus of the coliform group. 



4. 



« r v v 



Fig. 1. — B. typhosus. + 60 to phen. broth culture mixed with + 10 to phen. broth culture 



from same. 



In order to reduce the chances of error to the minimum I have, in 

 addition to rigid precautions against contamination to be described later, 

 submitted each strain of the organisms of the enteric group to searching 

 identification tests, cultural, biochemical, and serological, both at the 

 beginning, during the course of, and at the end of each set of observations, 

 the additional precaution being taken of frequent replating on MacKonkey's 

 medium and on agar, and of repeatedly restarting the whole process of 

 examination by subculture from fresh single non-lactose-fermenting colonies 

 on the former medium. 



