424 



SPORE CYCLE OF BACILLUS SUBTILIS 



seems to be near the limiting temperature for spore germination of 

 Bacillus suhtilis. Schreiber^ reports the germination of spores of this 

 organism at 8°C. after 7 days, but states that the spore cycle is not 

 completed at this temperature. 



Series II {25°C.). — This series was kept at room temperature, which 

 varied during the time of the experiment from 23.5-25°C. The 

 observations and results are given in Table III. 



TABLE III. 



Time in Hours Required by B. sublilis to Reach Various Stages of Development at 

 Different pH Values. (Temperature Approximately 25°C.) 



Figures represent average of four experiments. 



S indicates no apparent change except slight swelling and a certain loss of 

 refrangibility. 



* Few spores germinated; chains are short ; not all cells formed spores. 



The results in Table III show that at 25°C. the spores of Bacillus 

 sublilis germinated in broth at pH values from 5 to 10, while higher 

 and lower concentrations of hydrogen ions inhibited their develop- 

 ment. At pH 7 and pH 8, which are nearest the optimum hydrogen ion 

 concentration for this organism, germination took place in the shortest 

 time and multiplication was most rapid. 



^ Schreiber, O., Centralbl. BakterioL, Ite Abt., 1896, xx, 432. 



