BC 



UOPIXESS IN WATTLE liAKK: INFUSIONS, 



Talile viiiiz. -Percentage Composition of the Phases (Seventh day). 



Tlie indication that a moderate quantity of tannic acid tended to maintain 

 the stability of tlie introduced phase A2, led to the tannic acid tests being again 

 examined on the 10th day, when the following percentage counts, of the kinds of 

 colonies were noted. 



Table viiiA. — Percentage Composition of the Pliases with Tannic Acid (Tenth day) 



•Scanty growth. 



It appears that from 0.25 % to 0.5 % of tannic acid, when added to a syn- 

 thetic medium such as was used, maintains the stability of the A2 phase and 

 tliat smaller or larger quantities bring about its conversion to the less cohesive 

 l)liase Al. In contrast, phosphoric acid does not appear to have much influence ni 

 maintaining the stability, for on the 7tli day there was a 70 to 85 % conversiou, 

 irrespective of the amount of acid added. 



The limiting amount of tannic acid in this syntlietic medium for the phase A2 

 at the (iuic of making the experiment was 2 ""r and of phosphoric acid -|-30° 

 (equivalent to 30 c.c. of normal acid ]ier litre). 



The two last experiments with tannic acid in synthetic media indicated that 

 2% of the acid prohibited the formation of the ropy substance. It aiipcared to 

 l)c advisable to extend tlic line of experimentation and obtain some information 

 vegai-ding the action of tannic acid when added to an infusion of wattle-bark 

 capable of giving ropiness. With this object in view an infusion was prepared by 

 mixing three parts of water with two parts of bark, and filtering the li(|uid at the 

 end of two hours. Portions were seeded with .\2 and B2, and were treated with 

 progressively increasing (|uantities of tannic acid. The portions seeded with A2 

 did not develop ropiness and when examined on the 4th day they were found to 

 contain from 85 % to 05 % of Al. The portions seeded with B2 developed a pro- 



