14 



BACTERIA IN RELATION TO PLANT DISEASES. 

 Table 3. Chemical Behavior of Cane Gum and Bacterial Slime. 



Substance. 



Lead acetate 



Basic lead acetate 



Ammoniacal lead acetate. 



Barium hydrate 



Calcium hydrate 



Copper sulphate 



Ferric chloride 



Hydrochloric acid 



Alcohol 



Aluminum hydrate. . . 

 Dilute acetic acid. . . . 

 Glacial acetic acid. . . 

 Acid mercuric nitrate 



Xantoproteic reaction 



Sulphuric and phosphotungstic acids 



Acetic and tannic acids 



Acetic acid and potassium ferrocyanide 



Hydrochloric acid and potassium mercuric iodide 

 Sodium hydrate and copper sulphate 



Cane-gum. 



Precipitate 



....Do 



....Do 



....Do 



...Do 



....Do 



....Do 



Opalescence 



Slimy voluminous precipitate 

 in presence of salts 



Coagulation 



No precipitate 



Precipitate 



Precipitate soluble in excess; 

 no color reaction 



Color reaction 



Precipitate 



Opalescence 



Opalescence 



Precipitate on standing 



No biuret reaction, but pre- 

 cipitate 



Bacterial slime. 



Precipitate. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 

 Opalescence. 

 Slimy voluminous precipitate 



in presence of salts. 

 Coagulation. 

 Opalescence 

 Precipitate. 

 Precipitate soluble in excess; 



no color reaction. 

 Color reaction. 

 Precipitate. 



Opalescence and precipitate. 

 Opalescence. 

 Precipitate. 



No biuret reaction, but pre- 

 cipitate. 



The weakness of the solutions, owing to the limited amount of eane-gum at the dis- 

 posal of the experimenter, accounts, he says, for the absence of perceptible precipitates on 

 the addition of dilute acetic acid, and a mixture of acetic acid and tannic acid. No reac- 

 tions were obtained with KI 3 , AgN0 3 , KOH, BaCl 2 , NaOH, cone. HC1, picric acid, and 

 Adamkiewicz reagent. 



On precipitating the aqueous suspension [of the gum] three or four times with alcohol an opales- 

 cent alcoholic solution is obtained, from which the gum can be precipitated by small quantities of 

 neutral salts, such as NaCl. This fact, together with the reactions obtained with some of the 

 albuminoid reagents, suggested the similarity of the gum to the Mucins. That the Zoogloea-slime 

 of bacteria consists of mucin, or a substance nearly allied to it, has already been suggested, but there 

 are many points of difference between the bacterial slime and the mucins. The crude gum obtained 

 by precipitating the cultures with alcohol contains 6.1 per cent of ash and 3.08 per cent nitrogen in 

 the ash-free, dry substance. Repeated precipitation with alcohol, and also filtration of the gum 

 from the accompanying bacteria, would undoubtedly lower this percentage. It is, therefore, apparent 

 that the nitrogen content alone is sufficient to distinguish the slime from mucin or the allied muciuoids. 



In connection with this work Greig Smith made a variety of observations on the 

 cultural characters of the organism, and citations will be found under the heading "The 

 Parasite." 



When Dr. Went visited the West Indies for the Dutch government in the winter of 

 1902, the writer asked him to look particularly for this disease, but he reported that he 

 did not find it, although he said he had seen it in Java, where he had not regarded the 

 organism as a parasite. 



In 1904, following some very successful inoculation experiments, the writer published 

 a short paper on this disease, in the second part of the Centralblatt fur Bakteriologie. This 

 was subsequently translated into English and published in full by Cobb in his Third 

 [Hawaiian] Report on Gumming of the Sugar-cane (pp. 12-22). 



Cobb's Hawaiian report closes the history of this subject so far as known to the writer. 

 It contains a summary of Cobb's earlier papers, the translation referred to, a review of 

 Greig .Smith's work, and some additional observations which will be made use of elsewhere. 



See also in this connection "Sereh" (p. 72), "Top-rot" (p. 8i), and "Polvillo" (p. 85) 



