E. M. Doidgk 35 



was considerably slower, the organism preferring a medium which is 

 slightly acid to phenol-phthalein. 



A series of cultures was made to test the ability of the bacillus to 

 grow in media containing varying quantities of certain acids and 

 alkalis. 



To flasks containing 50 cc. of neutral broth were added different 

 percentages of acetic, oxalic, tartaric, and malic acids, and of sodium 

 hydrate and sodium carbonate. With each of these substances a 

 series of flasks was prepared varying in reaction from to ±50 of 

 Fuller's scale, the intervals between the reactions of any two in a series 

 being five degrees, so that there were ten flasks in each series. The 

 contents of each flask were pipetted into four tubes and these were 

 sterilised. A loopful of a young broth culture was introduced into three 

 tubes of each set and the fourth kept as a control. The results obtained 

 from the observation of these cultures may be tabulated as follows, 

 the controls in every case remained clear. 



Amount to Amount to 



retard growth inhibit growth 



Reactions in terms of Fuller's scale 



+ 30 

 + 35 

 + 40 

 + 40 

 + 35 



- 45 



- 35 



Atmosphere. That the organism is a facultative anaerobe was 

 suggested by the fact that it grew in the closed end of fermentation 

 tubes and in the depth of the medium in stab cultures, though in the 

 latter growth is never abundant. A series of cultures was therefore 

 made to test the ability of the bacillus to grow in the absence of oxygen 

 and in the presence of various other gases. Bulloch's apparatus was 

 used in making most of the anaerobic cultures, and the method used in 

 each case was similar to the one now to be described ; slight variations 

 in method were of course necessary in order to introduce the various 

 gases into the apparatus, but these are mentioned in connection with 

 the individual experiments. 



Oxygen and carbon dioxide absorbed. Streaks were made on slant 

 nutrient agar and glucose formate agar, and a loopful of a young broth 

 culture introduced into tubes of nutrient broth and glucose formate 

 broth. These were placed in a beaker standing in a glass basin at one 



3—2 



