BV R. GREIG-SIIITH. 61 



behave dili'ereatly to commercial tannic acid and this should be kept in mind 

 when interpreting: the results obtained in testing the commercial acid. 



A solution of dextrose, meat extract and mixed salts was prepared, and to 

 portions quantities of tannic acid rising from zero up to 0.6 % were added 

 before the addition of B'2. That with 0.1 <'f gave a faint ropiness and those 

 with 0.2 % to 0.5 Sc contained slimey striug-s. There was no pronounced ropi- 

 ness in any of them. 



As meat extract forms a precipitate with tannic acid, it was replaced by 

 asparagin. In this solution, B2 produced ropiness in the presence of 0.1 % 

 and 0.2 % of tannic acid. The control test and those with quantities greater 

 than 0.2 % ga\e a good growth of bacteria but no slime. 



The experiment was repeated with a slightly greater percentage of asparagin 

 (0.2 %) and dextrose (3 %) with mixed salts. Phase A2 gave ropy liquids 

 with the control and 0.1 % of tannic acid, but not with larger quantities. Phase 

 B2 only produced feebly gelatinous surface ring's with quantities of tannic acid 

 up to 0.2 Si:- 



A medium containing levulose, 3 %, asparagin, U.2 r^ and potassium citrate, 

 0.1 %, was prepared and .seeded with phases A2 and B2. The former was a very 

 active sUme producer when used and produced ropiness in the presence of quan- 

 tities of tannic acid up to 0.5% and a slight ropiness with 1 %. Phase B2 

 gave an evanescent ropiness in the flask containing 0.5 per cent only, and not in 

 any of the others. 



The influence of the original acidity of the medium was tested by means of 

 a solution containing dextrose, asparagin and mixed salts. One set had an 

 acidity to phenulphthaleiu of -|-17°, another was neutralised until the acidity was 

 -|-2.5°. Both were seeded with phase B2. That with -(-17'- gave no ropiness 

 in the control, a slight ropiness with 1 % of tannic acid and a distinct ropiness 

 with 0.2 % ; larger amounts were negative. With -|-2.5°, ropiness developed in 

 the control test only. Thus the production of ropiness was irregular. Phase B2 

 gave ropiness in the control with -(-2.5° and not with -[-17°; with -(-17'' and a 

 small cjuantity of tannic acid it produced a ropy fluid. 



In these experiments with tannic acid, either dextrose or levulose had been 

 used and with them a certain irregularity of effect had been obtained. It was 

 therefore deemed advisable to test the effect of other sources of carbon. As will 

 be seen later, the experiment with nitrogenous nutrients seemed to indicate that a 

 maximum amount of ropy substance would be formed in the presence of asparagin 

 or ammonium sulphate. Similarly, the saline experiments indicated that sodium 

 succinate was a favourable salt. Accordingly, media were prepared containing 

 asparagin or ammonium sulphate 0.25 %, sodium succinate 0.2 % and a source 

 of carbon 2 %. Tannic acid to the extent of 0.5 % was added to each flask after 

 infection, by which procedure a coagulation of the infecting droplet was avoided. 

 When a drop of infected bouillon, is added to a solution of tannic acid, the drop 

 is coagulated and the contained bacteria are probably prevented from being dis- 

 persed freely in the liquid. It is possible that much of the irregularity in the 

 previous experiments may have been due to this imprisonment of the bacteria. 



The gToups of flasks were seeded with A2 and B2. Another group was 

 seeded with Bl but as a plate, smeared at the time of infection showed that the 

 phase had become altered to B2, the group became a duplicate of B2. Phase B2 

 was pure, while A2 at the time of seeding contained 90 % of A2 and 10 % of Al. 



