BY R. GKEIC-SMITH. 



83 



- 16-5° 



(two days): good growth, colour bleached below condensed 

 water level and agar cracked with gas bubbles ; lower 2 cm. of 

 slope red and upper 3 cm. quite blue. 



(three days): gas buliblos in both, -12-8° blue and -16-5° 

 purple at top of slope. 



From these notes it is evident that the bacteria produce acid from saccharose, 

 that the gas produetion begins; when the alkalinity is about — 9.1° and is pro- 

 nounced at about — 12.8° and that the acid is possibly volatile at tiO", ;us was 

 shown by the rather persistent blue colour of the thin hiyers of medium. 



It had been found that the ordinary fluid media of tlie laboratory were not 

 well suited for the growth of the bacterium and that urea, meat extract, and 

 ammonia were useless as sources of nitrogen. Peptone water gave a fair growth, 

 while asparagin was a good nutrient. To see how far an alkaline condition would 

 improve matters, an experiment was made witli meat extract, ammonium phos- 

 phate, urea and asparagin all 1 %, with 1 % dextrose, salts and litmus solution. 

 Each tube received an increasing amount of sodium carbonate. 



Absolutely no gi'owtli occurred with urea and ammonia. Meat extract de- 

 veloped an acidity with the control and — 4°, and no growth appeared in the 

 others. 



In from two to six days the asparagin became acid and bleached with 0, 

 — 4°, — 8° and — 1()°, but no growth occurred in — 20°. In llj days gas 

 had shown in the tubes with from — 4° to — 12°, and, by the 20th day, gas had 

 developed in the control. Fresh tubes of asparagin were seeded from the — 8° 

 culture and these showed acid and bleaching in three days with the same strengths 

 of alkali as before. On the eighth day all the tubes up tt) — 16° were bleached 

 and contained gas. The fluids were all aUcaline to litnuis paper. Tliere was no 

 growth in — 20°. 



Litmus milk in five days was digested, bleached and was alkaline to litmus 

 paper. Unsterilised milk in four days was partly digested and was alkaline to 

 litmus paper. Several controls were unaffected. 



Meanwhile experiments were in progress to see if the thermophilic rod 

 could ferment tan-bark. The bark after sterilisation at 150° for an hour, was 

 wetted, seeded with the organism and heated at 60° in a current of air. Several 

 experiments which could only be considered as preliminary showed that certain 

 precavrtions were necessary. Heating the bark in flasks in an incubator at 60° 

 was unsuital)le, for the hot dry air caused the rubber corks to harden and the rubber 

 connections to loosen, with the result that the air and carbon dioxide were 



