354 LETHE E. MORRISON AND FRED W. TANNER 



Methods of study. Inoculations into the different media used in 

 this work were made either from twenty-four-hour agar slant cul- 

 tures or twenty-four-hour broth cultures. Since this work was 

 begun before the adoption of the new chart, the Descriptive Chart 

 of the Society of American Bacteriologists indorsed in 1914 was 

 used in the study of these thermophiles. The group number for 

 each culture was determined under as uniform conditions as pos- 

 sible. In the work that is now under progress on thermophiUc 

 bacteria from soil, canned foods, and other sources the Descrip- 

 tive Chart indorsed by the Society of American Bacteriologists 

 at the meeting of December 30, 1920, will be used. The index 

 number, it is beUeved, will give a better description of the or- 

 ganisms since it seems to embody characteristics which are more 

 important. 



Media and technic. With one or two exceptions the media 

 and technic used in this study were those recommended by the 

 Committee on the Descriptive Chart of the Society of American 

 Bacteriologists in their report on INIethods of Pure Culture Study 

 (1920); the cultures were, however, all grown at 55°C. Other 

 exceptions will be mentioned later. 



Morphologij. All the cultures studied were motile rods and 

 usually grew in chains containing from two to many individuals. 

 Sometimes chains of four or five rods showed an active snake- 

 like movement. The rods were both long and short; some had 

 rounded ends. Carbol fuchsin and Gram stains were used to 

 stain the smears; all were Gram positive except nos. 10, 20, 40. 

 Without exception, the cultures studied formed spores. Some 

 of the spores were central and some polar; some were oval and 

 some round; in a few cases the diameter of the spore seemed to 

 be larger than that of the rod and produced a sort of Clostridium 

 form. 



Nutrient broth. Witte's peptone was used in the nutrient broth 

 employed in this study, since it seemed to possess certain advan- 

 tages over other peptones. Good growth was secured with all 

 strains in nutrient broth at 55°C. Most of the cultures produced 

 turbidity and sediment in the broth; the surface growth in many 

 of the cultures was membranous or showed a heavy pelUcle. 



