130 BACTERIAL ORIGIN OF GUMS OF ARABIX GROUP, 



is sufficient to show that the gum is a bacterial and not a yeast 

 product. This is important because the gummosis (? gum-flux) 

 of the plum has been ascribed to a similar dematium-3'east by 

 Massee."^ 



The investigation showed that (1) the gum that exudes from 

 peaches is formed in the stem and branches; (2) it has a bacterial 

 origin, and (3) it is produced chiefly b}' Bad. acacice. 



VIII. — The Gum-flux of the Almond. 



The gum-flux of the almond showedf many points in common 

 with the gum-flux of the peach. 'J'he fresh gum that exuded 

 from punctures and cracks in the fruit was of the same colourless, 

 almost transparent appearance and gelatinous consistency, and 

 when examined microscopical 1}^ the same badly staining short 

 bacterial forms were observed. Moreover, when glucose-sjelatine 

 plates were prepared with media infected with portions of fresh 

 gum and gum-saturated fruit-tissue, bacterial colonies were con- 

 spicuous by their absence; colonies of yeast-like organisms Mere 

 obtained. 



As in the case of the peach, many bacterial colonies and but 

 few yeast colonies developed upon plates which were prepared 

 with media infected with portions of twigs, the exterior of which 

 had been sterilised by passage through a flame. The bacteria 

 consisted chiefly of Bact. acaciw. The other colonies, which were 

 few in number, included Bac. levaniformans, the gum-levan 

 organism, and the slime-forming bacillus which had been first 

 isolated from the peach and which has been named Bact. persicce, 

 n.sp. The dematium-3"east also obtained from the peach was 

 isolated, but as it constituted about 1 % of the colonies, it pro- 

 bably had little effect in determining the composition or nature 

 of the gum. 



The investigation showed that (1) the gum-flux of the almond 

 is identical with the gum-flux of the peach; (2) the gum is a 



* Massee, Kew Bulletin, 1899. 

 t The specimens of aftected fruit were sent by Mr. Fred. Steward, Adelaide. 



