BACILLUS LUTEUS. 359 



margin. The whole gelatine gradually assumes a 

 greenish colour. In puncture cultivations a whitish 

 layer is formed along the track of the needle, and at the 

 point of entrance of the needle a small funnel-shaped 

 depression appears, containing at the lower part liquefied 

 gelatine, and at the upper part air. The liquefaction 

 gradually spreads until it reaches the wall of the glass, 

 and slowly extends downwards ; at the bottom of this 

 liquefied material, a thick, whitish deposit is formed. 

 Beneath the area of liquefaction the gelatine has a 

 greenish-yellow fluorescing appearance > the liquefied 

 mass does not show the play of colours so markedly. On 

 potatoes a brownish deposit is formed, which, however, 

 is not characteristic. 



Among the bacilli which produce greenish colouring matter Greenish 

 should probably be placed the organism described by Engel- coloured 

 maim as bacterium clilorinum, and by van Tieghem as ba-c- 

 terinm viride and bacillus virens, in which the substance of 

 the cell itself presents a greenish colour. The species in- 

 vestigated by Engelmann was an oval, very mobile rod, 2 to 8 

 /*. in length; the bacilli investigated by van Tieghem were 

 non-motile. It is, however, riot impossible that in all three 

 cases these authors had to do with fission algae ; we must 

 await a more accurate description. 



Bacillus luteus.* 



This is a short bacillus of medium thickness, and Yellow 

 apparently non-motile. It forms in gelatine plates 

 deeply placed colonies, of a lentil or whetstone form (as 

 seen under a low power), at times with irregular out- 

 lines, at times with sharp smooth contour, and of a 

 brown colour. The superficial colonies are 10 to 20 

 times larger, they measure 2 to 3 mm. in diameter, and 

 appear round, often irregular in outline, of a light brown 

 colour, and with a whitish, clear, transparent margin. 

 Macroscopically, the colonies are yellow and opaque ; in 

 puncture cultivations a yellow growth is formed both 

 along the track of the needle and also on the surface, 



* Gottinger hyg. Institut. 



