BY R. GREIG SMITH. 755 



while the upper layers become turbid and a white wrinkled film 

 forms on the surface. The film darkens, and a black pigment is 

 diffused into the upper layers. A strong indol reaction was 

 obtained. No nitrite is formed from nitrate. Milk is first 

 thickened, then the casein is peptonised. The colouring matter 

 is not quinone, since no blue colour is obtained with potassium 

 iodide and starch in acid solution. The black pigment is not 

 formed in gelatine or milk. 



The organism was separated by means of Parietti's solution 



Bacterium T. 



The organism is an actively motile cocco-bacterium measuring 

 0'4 :0 - 6^; it does not stain by the Gram method. When free 

 to grow upon agar, the colonies become amoeboid and translucent 

 or iridescent white. The processes when magnified are seen to 

 have a semilunar shaded tip like a finger-nail. The stroke on 

 agar is porcelain-white, raised and glistening; the base is spread- 

 ing, the margin irregular, and the edge smooth. In old cultures 

 a brownish colour diffuses into the medium. Litmus-lactose-agar 

 is unaffected. In gelatine the liquefying colonies are circular 

 and crateriform with a white centre. Microscopically the centre 

 is coarsely granular and the margin indefinite. The stab in 

 gelatine becomes saccate, and the liquefied medium turbid, 

 without film or precipitate. Gas is not produced from glucose. 

 Bouillon becomes turbid and forms a sediment, but no film; the 

 indol reaction was obtained. Nitrates are reduced to nitrites. 

 Milk is coagulated at 37° with a neutral reaction. On potato a 

 raised, irregular, dry, yellowish-white layer is formed; the colour 

 becomes ivory-white and moist glistening. 



This bacterium apparently differs in size only from Bac. 

 aquatilis communis, Zimm. It was found in the tube containing 

 7 drops of Parietti's solution per 11 5 c.c. of suspension and 

 bouillon (300 c.c. water). If the organism is the same as 

 Zimmermann's, it seems peculiar that the disinfectant should 

 have permitted the growth of what is described as the commonest 

 water bacterium. 



