36 



THE GUMMOSIS OF THE SUGAR-CANE, 



elude that in the suspension the bacteria are inert, and for 

 purposes of identification of the gum it is unnecessary to 

 separate them. 



In testing the bacterial slime and the cane-gum a number of 

 reagents suggested themselves, and the results of the numerous 

 tests which identify the two are shown in the following table. 

 In considering the tests it must be borne in mind that the cane- 

 gum at my disposal was very limited, and the solutions con- 

 sequently were weak, which accounts for the absence of perceptible 

 precipitates on the addition of dilute acetic acid and a mixture 

 of acetic and tannic acids. 



The Chemical Reactioxs of the Gum fkom Caxe and of the Bacterial 

 Slime formed in Laboratory Cultures. 



Cane-Gum. 



Bacterial Slime. 



Lead acetate 

 Basic lead acetate 

 Ammoniacal lead acetate 

 Barium hydrate 

 Calcium hydrate 

 Copper sulphate 

 Ferric chloride ... 

 Hydrochloric acid 

 Alcohol .. 



Aluminium hydrate 

 Dilute acetic acid 

 Glacial ,, ,, 

 Acid mercuric nitrate 



Precipitate. 



Opalescence. 



Precipitate. 



Opalescence. 



Slimy voluminous ■ Slimy voluminous 

 ppt. in presence of ppt. in presence of 



Xanthoproteic reaction 

 Sulphuric and phosphotungstic 



acids 

 Acetic and tannic acids 

 Acetic acid and potas. ferro- 



cyanide 

 Hydrochloric acid and potas. 



mercuric iodide 

 Sodium hydrate and copper 



sulphate 



salts. 

 .1 Coagulation. 

 .j No precipitate. 

 .! Precipitate. 

 .1 Ppt. soluble in ex- 



j cess ; no colour re- 



I action. 

 . Colour reaction. 



Precipitate. 

 Opalescence. 



Opalescence. 



Ppt. on standing. 



salts. 

 Coagulation. 

 Opalescence. 

 Precipitate. 

 Ppt. soluble in excess; 



no colour reaction. 



Colour reaction. 



Precipitate. 

 Opalescence and pre- 

 cipitate. 

 Opalescence. 



Precipitate. 



No biuret reaction » 

 but ppt. 



No biuret reaction 

 but ppt. 



No reactions were obtained with KI.^, AgNO.j, KOH. BaCl.^. NaOH, cone 

 HCl, picric acid, Adamkiewicz reagent. 



