BY R. GREIG-SMITH. 



269 



grown upon media with a plant basis are acid as a rule, but if 

 they are not distinctly so to litmus paper, it is advisable to add a 

 drop or two of dilute sulphuric acid before they are heated in the 

 autoclave in order to ensure the complete formation of gum-acids. 

 The gums, which are really gum-acids, were obtained from the 

 slimes of a number of races of Rhizobium and were tested in the 

 usual manner, that is, by adding a drop of reagent to a drop of 

 the thick sum mucilage. The following results were obtained : — 



Reaction of the G 



UMS OF VARIOUS 



Races of Rhizobium, etc. 





Maero- 



Lupin 



Pea 



Bean 



Vibrio 





zamia 



(Krai) 



(Krai) 



(Krai) 



denitrificans 



Alcohol 



+ 



t 



T 



t 



t 



Basic lead acetate 



t 



t 



t 



t 



t 



Ammoniacal lead acetate 



t 



t 



T 



t 



t 



Neutral lead acetate .. 



t 



X 



t 



t 



X 



Barium hydrate 



* 



* 



t 



t 



* 



Ferric chloride ... 



t 



t 



t 



t 



X 



Copper sulphate 























CuS0 4 (dil.) followed by 













KOH 



t 



t 



t 



t 



t 



Phosphotungstic acid ... 



t 



t 



t 



t 



t 



Fehling's solution 























Amrnoniocupric hydrate 























Milk of lime 























Silver nitrate ... 























Iodine ... 























Tannic acid 



? 



? 



? 



? 



? 



Sulphuric acid ... 







X 



t 



~ 



f, a clot or coagulation; x, thickened; *, a slight precipitate; ?, an 

 opalescence; 0, no reaction; — , not tested. 



The race "Macrozamia," as I have mentioned, was obtained from 

 the gum of a Macrozamia spiralis that grew on the margin of a 

 plot of ground which bears a crop of Blue Lupins every year. 

 The races " Lupin (L. luteus), Pea (P. sativum), and Bean (Vicia 

 fabaj" were obtained from Krai of Prague, while Vibrio denitri- 

 ficans was originally isolated from the Sydney water supply. 

 Bearing in mind that in these tests a thickening is really an 

 incipient coagulation and that a precipitate is a partial clot, one 

 can see that these gums have virtually the same reactions. 



