BY R. GREIG-SMITH. 



65 



It is clear from the experiment that tlie phase Al is capable of producing- 

 ropiness in the presence of from 0.5 % to 1.25 % ofi tannic acid in a medium 

 containing galactose. With 0.25 % there was no ropiness formed, and as the 

 acid increased, so did the viscosity. Tannic acid or, possibly, acidity seems 

 therefore to be a sine qua non for the foi-mation of ropiness by this phase of the 

 . liacterium A. 



The phase A2 at the time of the experiment was a strong slime-foi-mer, and 

 gave a pronounced ropy solution in the presence of amounts of tannic acid up to 

 ] %. The ropy substance had been formed in the early days of the experiment, 

 and it did not alter, although the phase in the ease of 0.5 % of tannic acid 

 changed to a mixture of phases, and in the case of 1 % it changed to Al. 



The phase B2 gave ropiness in amounts of tannic acid up to 2.25 %, but the 

 viscosity of the solutions was never so pronounced as in the ease of A2. The 

 most viscous solution was obtained in the presence of 1 % of tannic acid. 



The experiment shows that the three phases which were tested produced 

 ropiness in synthetic media when the tannic acid varied in amount up to 1.25 % 

 or 2.25 %, and that the tendency of the bacterial phase A2 is to change, in the 

 presence of tannic acid, to Al, and for the bacterial phase B2 to remain constant. 



The same galactose medium was used to determine the comparative amounts 

 of tannic acid and of phosphoric acid necessary to prevent the formation of ropi- 

 ness by phase A2. 



Table viii. —Tannic and Phosphoric Acids compared. 



Certain of the cultures were examined at the end of the first day, and they 

 were found to contain the introduced phase, A2, in pure culture. They were 

 again examined on the seventh day and it was found that the phase had altered 

 to Al. 



