138 BACTERIA AND THE GUM OF IIAKEA, 



wards it became liquid. The stab-culture in the same medium 

 developed as a rough thread at the top of which stood a wrinkled, 

 semi-transparent, whitish nail-head. The upper layers of the 

 gelatine became liquefied in a stratiform manner. Upon nutrient 

 agar the culture was at first narrow and dirty-white or yellowish 

 and raised with a slightly wrinkled Hat margin. The growth 

 became broader and the wrinkles more pronounced, while the 

 centre deepened in colour to buff. The potato-culture was buff, 

 raised and dr}-. Bouillon became very turbid, producing a film 

 and a coherent sediment. The indol reaction was obtained and 

 nitrates were reduced to nitrites. Milk became slightly viscous. 

 On saccharose-potato-agar the growth was luxuriant, convex, 

 slimy and dirtj^-white; the margin was flattened and rough and 

 the condensed water became a thick slime. The organisms 

 generally exhibited polar staining, and they were negative to 

 Gram's method. The cells, which were motile, varied in size. 

 In bouillon they ranged from 0*5 : 0*7 /x to 0-75 :1 -5 /x, but 

 generally measured 6 : 12 jx. On saccharose-potato-agar, they 

 varied from 0-3 : O'S^ to 0-7 : 1-2 /.. 



The nature of the colonies on glucose-gelatine (indicative of 

 the production of an insoluble gum), as well as the slow liquefac- 

 tion of the medium, show that the bacterium has its nearest 

 allies in Bact. metarahinum and Bac. atherstonei. 



A quantity of the slime svas prepared by growing the organism 

 on a medium containing saccharose 20, potato-juice 100, glycerine 

 10, tannin 3, and agar 20 grm. in the litre. A prescription 

 almost similar had been used originally in growing the slime of 

 Bact. 7netarahinv.n), but it had been subsequently discarded, as 

 no slime could be obtained upon it. The slime tended to adhere 

 to the agar, but this was overcome by pouring about 10 c.c. of a 

 nutritive fluid over the grosvth in each plate. The nutritive 

 fluid consisted of the levulose-asparagine fluid, the prescription 

 for which has already been given, and it was used because it 

 chanced to be convenient at the time. The slime yiekled a gum 

 by the autoclave treatment. This gum, when dehydrated, 

 absorbed water, becoming a thick mucilage. It did not dissolve 



