4:50 THE RED STRING OF THE SUGAR-CAKE, 



contained many bacteria. A transverse section of one of the red 

 bundles showed that the colour was caused by the presence of a 

 red gum in the large vessels (PI. xv., fig. 12). A red gum is also 

 found in the Sereh Disease and in Red Smut, concerning both of 

 which Went says that the gum is not caused by bacteria. 



Other examples which I investigated were canes which were 

 undoubtedly affected with gummosis; these were of the Chenoma 

 variety which had been grown upon low-lying, poorty drained 

 land. 



Portions of the red strings were cut out with a sterile knife 

 under aseptic conditions, and were inserted into tubes of molten 

 ordinary glucose-gelatine, which after standing for an hour or 

 two at 30' were poured into Petri-dishes. From the first and 

 second samples I ultimately obtained a mould and several 

 bacteria. In glucose-gelatine the mould produced a brilliant 

 crimson- scarlet colour, and it undoubtedh' was the agent which 

 Avas primarily responsible for the colour of the strings. But 

 from the presence of gum in the vessels I was of the opinion that 

 the mould was accompanied by a slime bacterium, and that the 

 complete phenomenon of red gum was brought al^out by the 

 simultaneous growth of two organisms, a mould and a bacterium. 

 This view was confirmed during the research. It may, however, 

 be mentioned here that every portion of red vascular bundle 

 that was taken did not contain the mould, but did contain slime- 

 forming bacteria; and from this we must conclude that the mould 

 does not accompany the gum along the whole length of the 

 string, but colours the gum which is carried along the vessels, 

 perhaps by sap-pressure, perhaps by bacterial growth, or that 

 the rapid growth of bacteria starves out the mould after the 

 colour has been produced. At any rate two things are certain, 

 (1) the mould can under certain conditions produce the colour 

 and cannot produce slime, and (2) the bacteria do produce slime. 



In the original case three bacteria had been isolated. One of 

 these I shall for convenience call the white slime bacterium, 

 another was Bad. sacchari, the third was a race of Bad. fiiior- 

 escens liquefaciens. To test which of these would produce a 



