168 BACTERIA AND THE GUM OF LINSEED MUCILAGE, 



a relatively thin gum. When hydrolysed, the gum gave off 

 furfural and 3^ielded a solution which reduced Fehling's solution. 

 Treatment of this solution with phenylhydrazine solution gave 

 galactosazone and tarry impurity. 



With regard to the tarry impurity, I showed in my work upon 

 Hakea gum that the impurity is formed by the action of the 

 phenylhydrazine solution, or even of dilute acetic acid upon cer- 

 tain indefinite osazone-like bodies which are formed from indefi- 

 nite reducing substances, probably akin to the furfuroids of 

 Cross, Bevan and Smith. These are found among the products 

 of hydrolysis of every vegetable gum."^ In some cases, as in the 

 natural and artificial product of Bact. acacue, the definite sugars, 

 arabinose and galactose, preponderate in the products of hvdro- 

 tysis and the tarry imparity is rapidlj^ sejDarated. In other cases, 

 as in Linseed gum, Hakea gum and the gums of organisms "a " 

 and " b," the definite sugar galactose is in small am.ount, and the 

 tarry body preponderates to such an extent as to make it evident 

 that the gums are hydrolysed to the furfuroid bodies chiefly. 



As in the case of the gum of Hakea saligna, the indefinite 

 nature of the products of the hydrolysis of Linseed gum militate 

 against the possibility of being able to trace the source of the 

 gum to any organism. It must, however, be borne in mind that 

 Linseed mucilage is admitted to consist of a gum and of cellulose. 

 The latter is not generally formed by bacteria (the only known 

 case being that of Bact. xijlinum^ the vinegar bacterium), and it is, 

 therefore, possible that the gum, while being originally produced 

 by a bacterium or by several species of bacteria, is altered by the 

 host-plant into the mucilage which we find. 



The arguments in favour of such a view are man}'. We can- 

 not conclude that the gum has not a bacterial origin, because it 

 does not exude from the plant like other recognised bacterial 

 gums. As a rule, it is only when the plant is surcharged with 

 gum that it exudes from punctures, cracks or other wounds. 



* The so-called galactan gums give the furfural reaction, e.g., the gum of 

 Bact. saccliari. 



