BY R. GREIG SMITH. 129 



of stained gyum films, they were considered as having notkin<->- to 

 do with the production of the gum. 



The presence of dead bacteria in the gum found inside the fruit 

 points to the gum being formed in the stem, and being forced 

 into the rapidly growing fruit, where the bacteria aie killed by 

 the greater acidity of the fruit juices as compared with the stem 

 fluids. If this be the case the bacteria which produce the gum 

 should be found in the vessels of the twigs attached to the fruit. 

 To test the matter fresh specimens of gummed peaches were 

 obtained from Mr. Potts, and from these new cultures were made. 

 The colonies that grew upon plates which had been infected with 

 the twigs to which the fruits were attached consisted chiefly of 

 Bact. acacice. The others consisted of the slime bacillus (Bact. 

 persic(e, n.sp.), Bac. levamformans, and a dematium-yeast which 

 appeared capable of producing slime. From eight portions of 

 gum and fruit pulp of the new specimens of fruit there were 

 obtained an inert bacillus, an inert coccus, an inert sarcina, and 

 many colonies of a small 3^east and the dematium-yeast. In the 

 twigs the yeasts were in the small minority, while in the fruit 

 they predominated. 



From this investigation it appears that the gum which exudes 

 from punctures and wounds upon peaches, and is found satu- 

 rating the soft tissues, has been formed in the stem and 

 branches. The bacteria which produce the gum are chiefly 

 Bact. acacicE, but other bacteria also contribute, and the chief of 

 these is the slime bacillus, Bact. per sicm, n.sp. Baci/his levani- 

 formans is practically inert, for the gum levan that it produces 

 would be immediately hydrolysed. This organism may, by 

 virtue of its inverting action, play a part in assisting the 

 other bacteria to produce gum, but this is doubtful. 



The dematium-3'east grows as a tough skin upon saccharose- 

 potato-agar, and possibly consists of cells cemented together or 

 'embedded in a slime matrix. It will form the subject of a future 

 investigation. But even should it be proved to be capable of 

 producing slime, its practical absence in film preparations of the 

 fruit gum, and the overwhelming majority of bacterial remains, 

 9 



