BY R. GREIG SMITH. 251 



formed in fluid cultures, the organism did not lend itself to 

 determinative experiments, such as those that had been made 

 with Bad. acacias. Still so far as they went, the appearances of 

 the agar cultures seemed to show that what favoured the one 

 organism also favoured the other. 



The rapid subcultivation upon saccharose-potato-agar produced 

 a growth which indicated that the gum was more insoluble than 

 at the time when the cultural characters of Bad. ^netarahinum 

 were described. At what may be called the height of its 

 development, that is when the gum is most insoluble, the growth 

 on the different media are much drier and more wrinkled than 

 have been described. The colony on glucose gelatine as illus- 

 trated is typical of the organism after it has been cultivated for 

 a short time in the laboratory, say from the 5th transfer onwards. 

 Up to the 5th subcultivation the colony has not the regular 

 wrinkled formation, but appears as an irregular moruloid colony. 

 The coarsely granular structure of the glucose-gelatine colonies 

 of Bad. acacice is apparent, even in the colonies upon the first, 

 i.e., the original plate. A typical colony of Bad. para^-abinum 

 has been reproduced in order to complete the set of the arabin 

 bacteria. It is by the appearance of the colonies on nutrient 

 glucose gelatine that the bacteria can be most easily diagnosed. 



The conclusions that may be drawn from the research are as 

 follows : — 



1. Baderium acacice can produce gum readily in the presence of 



suitable nutrients. 



2. Levulose and saccharose are the best sources of carbon; 



maltose, mannite and glycerine come next, whilst dextrose, 

 galactose, lactose and raffinose are of no use. 



3. The organism acquires and readily loses the power of utilising 



saccharose. 



4. Dextrose or galactose prevents the gum being formed from 

 levulose or maltose. 



5. The bacterium temporarily loses the power of forming gum 



when subcultivated upon sugar-free media. 



6. Molasses can be employed for the production of gum. 



