BY R. GREIG SMITH. 547 



osazone melting at 159^. The second fraction dried as a loose 

 yellow powder with a brown tinge. It melted at 184-186^. The 

 third fraction dried as a loose yellow powder which melted at 

 190-191'^. This was dissolved in hot alcohol, and hot water was 

 added until a workable precipitate settled out. The clear yellow 

 powder so obtained was galactosazone melting at 194''. 



The slime has thus been seen to contain a carbohydrate which 

 had the properties of pararabin, viz., upon drying it became 

 insoluble, and this modification was insoluble in dilute alkali, 

 soluble in dilute acid; it could not be hydrolysed by boiHng with 

 dilute acid, but by appropriate treatment with strong sulphuric 

 acid it was hydrolysed to arabinose and galactose. 



Invertase is not secreted. — Many bacteria while producing gum 

 from saccharose invert apart of the sugar to levulose and dextrose, 

 one of which may be utilised. This organism does not secrete 

 invertase. The supernatant liquid from saccharose-chalk cultures 

 did not reduce Fehliiig's solution. Instead of reducing the fluid, 

 the gum formed a precipitate which coagulated on boiling. 



The influence oj various sugars, i^c, upon slirne-Jorviation.— 

 In the culture media hitherto employed saccharose had been the 

 carbohydrate nutrient. But as other carbohydrates might be 

 capable of replacing saccharose, experiments were made to investi- 

 gate this question. The results showed that dextrose, levulose, 

 galactose, mannite and glycerine could replace saccharose. Of 

 these levulose and glycerine were better than the others, and 

 better even than saccharose. The following carbohydrates were 

 useless : rafiinose, lactose, maltose, inulin, starch and dextrin. 

 The experiments were made with a peptone and chalk fluid, and 

 also with nutrient meat-agar, to both of which media the carbo- 

 hydrates had been added previous to sterilisation. The fluid 

 cultures corroborated the results obtained with the agar medium. 

 Potato-ex tract-agar was also used, but as this medium contains 

 reducing sugars, it did not show clearly the eff'ect of the added 

 carbohydrates. There was one exception, however. The addition 

 of glycerine produced a gelatinous growth, the bacteria being 



