278 FORMATION OF SLIME OR GUM BY RHIZOBIUM LEGUMINOSARUM, 



The experiments were repeated, and in No. 2, which follows, 

 the reaction of the medium after the slime had been scraped off 

 was tested. 



The Influence of Dextrose and Levulose upon Saccharose. 



Medium as 

 in previous 

 experiment 

 with 2% of 



Expt. 1, 

 19/3/'06. 



Expt. 2, 9/4/'06. 



Lupin (Krai) 



Pea (Krai) 



Pea(March) 



Fr'nchBeanjMacrozamia 



Phos- 

 phate. 



Cit- 

 rate. 



Phos. 



Citr. 



Phos. 



Citr. 



10* 



23* 



Ot 



Phos. 



lOt 

 lOt 



It 



Citr. 



10* 



14* 



It 



Phos. 



lOt 

 lOt 

 lit 



Citr. 



10* 

 13* 

 11* 



Saccharose, 

 = 10 

 Dextrose, 

 Levulose, 



10 



6 



23 



10 

 2 

 5 



lOt 

 14t 



5t 



10* 

 9t 



2t 



lOt 



12t 



It 



Saccharose, 

 actual % 



3 



16 



3 



15 



11 



5 



7 



14 



10 



8 



t, means an acid reaction of the medium after removal of the slime. 

 *, an alkaline, and {, a neutral reaction. 



So far as the identity or otherwise of the races is concerned, 

 these results indicate the same thing that was found with the 

 individual sugars, viz., that the races fall into three groups,— 

 (1) Lupin, (2) Peas and Bean, and (3) Macrozamia and Robinia. 

 But they also show that the Pea (Krai) race differs from the 

 Australian race with respect to the action of phosphate or citrate 

 in reducing the actual yield. 



The reaction of the medium at the end of the experiment, when 

 considered with the comparative yields of slime, shows that 

 levulose probably produces an acid which is injurious to the 

 composite bacterium, and this is in all likelihood the reason for 

 the poor yield of slime. Could the acid be neutralised as it is 

 produced the slime might be much greater. This was tested by 

 repeating the experiment with some of the races, the medium 

 being mixed with 1 % of chalk and the phosphate being added at 

 the time of preparing the plates. 



