130 BACTEEIOLOGY 



disc notched in a radiating manner at the margin, round 

 which a light brownish circle runs, and this again is 

 surrounded by a second circle of a brightly-shining appear- 

 ance, so that the surface of the gelatine appears marked 

 with concentric rings. A dirty grey deposit forms on 

 potato. 



Diplococcus luteus. — This diplococcus, fo£nd by Adametz, 

 forms rather long chains, whole pieces of which move about 

 in a lively manner in the hanging drop. It liquefies gela- 

 tine slowly and forms round brownish -yellow colonies which 

 spread with tolerable rapidity. In thrust-cultures the 

 growth is more active on the surface, showing lemon- 

 yellow deposits in concentric layers. It appears on agar 

 as a yellow or brownish-red coating, while that on potato is 

 dirty yellow and exhales a mouldy odour. Caseine is precipi- 

 tated from milk by cultures of the micro-organism. 



Bacillus fluorescens liquefaciens and Bacillus nivalis 

 (glacier-bacillus). — These both display short, thick rods 

 possessing the power of easy movement. Fick found the 

 Bacillus fluorescens liquefaciens also in the conjunctival 

 secretion, and Schmolk found the Bacillus nivalis in glacier 

 ice. Both form on the gelatine plate colonies which have 

 a funnel-shaped hollow in the centre, and exhibit a greenish- 

 yellow fluorescence. Thrust-cultures grow slowly in the 

 deeper part, but somewhat more rapidly in the case of 

 Bacillus fluorescens liquefaciens than in that of Bacillus 

 nivalis, and the former shows on the surface a depression 

 resembling an air-bubble, owing to evaporation, whereas 

 with the latter the liquefaction extends over the gelatine. 

 The non-liquefied portion of the medium shows a greenish- 

 yellow fluorescence. A whitish layer appears on agar along 

 the inoculated streak, and the mass becomes fluorescent. 

 The deposit on potato is yellowish-brown. 



Bacillus fluorescens non-liquefaciens. — A bacillus closely 



