41 



culture media, when not interfered with by the brown pigment, gen- 

 erally gamboge, chrome j^ellow, or canary j^ellow, but sometimes paler. 

 Old cultures on some media darken from the production of a soluble, 

 pale-brown pigment. This feeble brown stain is best developed in 

 hyacinth broth, in potato broth with peptone, on turnips, on radishes, 

 and on banana rinds. It was not observed in acid or alkaline beef 

 broth, on coconut flesh, on sugar beets, in nutrient starch jelly, in agar, 

 or in gelatin, with or without sugar. This organism grows readily on 

 potato cylinders standing in distilled water, but it never becomes copi- 

 ous or fills the water with a solid yellow slime, owing to its feeble dia- 

 static action. Potatoes on which it has grown, even for several months, 

 always give a strong starch reaction with 

 iodine. It behaves the same on nutrient 

 starch jelly free from assimilable sugars. It 

 liquefies nutrient gelatin and Loetfier's blood 

 serum, but does so slowly, and will not liquefy 

 gelatin at all if 10 per cent cane sugar is added 

 (fig. 6). Growth on nutrient agar or nutrient 

 starch jellj^ is inhibited (unless the inocula- 

 tion be from a solid culture and very copious) 

 by the addition of 10 per cent glycerol, and is 

 greatly retarded bj" 5 per cent glj'cerol ; even 



2i 



per cent of glycerol retarded growth. 



Growth in beef broth was much retarded by 

 the addition of 1.5 per cent sodium chloride. 

 Organism extremely sensitive to plant acids, 

 including those of the hyacinth. Aerobic; 

 doubtfully, if ever, facultative anaerobic; not 

 a gas producer (see fig. 5). Does not redden 

 litmus milk, but makes it bluer, and slowly 

 separates the casein from the whey b}' means 

 of a lab ferment. Produces under some cir- 

 cumstances, and slowl}^ a small amount of 

 nonvolatile acid (slime acid?) with various 

 sugars (grape, cane, etc.), which acid is fre- 

 quently obscured by the moderate production 

 of alkali. In the presence of air produces an organic acid (probably 

 acetic) from ethyl alcohol dissolved in milk or bouillon. Inverts cane 

 sugar, but apparently without the intervention of any enzym. Will not 

 grow on 30 per cent grape-sugar agar. Resists dry air very well, i. e., 

 more than forty-eight days when spread on cover glasses in thin layers. 

 In Dunham's solution with methylene blue the color is reduced in 

 a few days, but reoxidizes quickly on shaking; final color (56 days) 

 bright blue. In Dunham's solution with indigo carmine the color 

 changes to a briglit blue, which persists for a long time; final color 

 yellowish. In Dunham's solution with rosolic acid and enough IICI 



Fig. 5.— Typical behavior of Ps. 

 hyacinthi in fermentation 

 tubes containing peptone 

 water, or peptonized beef 

 bouillon, with addition of vari- 

 ous sugars and other carbohy- 

 drates. Fluid clear in closed 

 end, clouded in U and open 

 end. 



