Morphological Studies in the Life- Histories of Bacteria. 473 



entirely to avoid the use of plugs of wool, and to inoculate, or withdraw 

 fluid from, the tubes with sterile Pasteur pipettes in the actual flame of a 

 Bunsen burner. The use of these flasks also gave an absolute guarantee 

 that only clean vessels were employed, each flask being heated to not less 

 than 300° C. before use. 



Fig. 2. — B. coli communis. Acid broth + 20 to phen. mixed with broth sub-culture 



from same. 



4. Deposits were obtained in all cases by centrifuging for three to five 

 minutes the broth in small pointed serum tubes, each tube being sufficiently 

 heated before filling to ensure carbonisation, and subsequent destruction of, 

 any material left after routine cleaning by previous use. In this way it 

 was possible to be certain that no organisms foreign to the inoculated broth 

 under observation were present in the tubes employed. 



5. All glass slides for microscopical examination were treated in the same 



