BY R. GREIG SMITH. 595 



The formation of gum and the inversion of the sugar are seen 

 to go on steadily from the second day until a balance is practically 

 established between the constituents on the seventh da}-. The 

 saccharose is not entirely inverted, nor is this to be expected. 

 Marshall Ward and Reynolds Green^ found a complete inversion 

 of saccharose with their sugar bacteria, but it is just possible that 

 this was brought about by the acid fluids (their organism produced 

 in the culture fluid 0-7 % acetic and 0-057 % succinic acids) during 

 the chemical manipulation and not by the invertase secreted by 

 the organism. Even with the small amount of acid in my cultures 

 I noted in my preliminary experiments an increase in the invert 

 sugar when the acids were not neutralised. The acids formed by 

 the bacillus have also a solvent action upon the gum. In one 

 case I obtained 31 grms. per litre of crude gum as against 29 grms. 

 when the acidit}^ was not neutralised during the precipitation 

 with alcohol. 



The Influence of varying Amounts of Peptone. 



The bacillus can grow with marked action upon saccharose in 

 exceedingly poor nutrient solutions. The solutions in which the 

 action has been already shown contained only Jg- % of peptone. 

 With smaller amounts the formation of gum is evident from the 

 appearance of the cultures, although the action is naturally not 

 so rapid. With the object of determining the influence of pep- 

 tone on the fermentation, a series of cultures containing varying 

 amounts of peptone, but with the other constituents as before, 

 were made and analysed upon the same, viz., the fifth, day. 

 The results expressed in terms of 100 parts of original saccharose,. 

 i.e., in parts per litre of culture fluid, are given in the table, and 

 are also plotted upon the curves that follow. 



* Ward and Green, Proc. Eoy. Soc. Ixv., No. 414, 79. 



