144 MICRO-ORGANISMS AND FERMENTATION. 



There is a rich formation of slime in 10 to 30 per cent, 

 nutrient sugar solution, whereas none occurs in similar grape- 

 sugar and milk-sugar solutions. The species has a pronounced 

 demand for oxygen, and the cells exhibit movement at certain 

 stages. It appears to occur both as rods and coccus forms, 

 according to the composition and reaction of the substratum. 

 It liquefies alkaline gelatine. In a stab-culture on agar it 

 grows as a moist glistening whitish deposit, which forms two 

 zones, the inner wrinkled and the outer smooth. Brautigam 

 isolated a Micrococcus from an infusion of digitalis leaves, 

 which converted a nutrient sugar solution into a complete 

 jelly, and made apple juice viscous. In a similar infusion 

 Happ found a slime-forming rod bacterium (Bac. gummosus) 

 5 to 7-5 /x long, 0-6 to 2 /u. wide. It assumes spindle shapes 

 in old cultures, and is sometimes motile. On neutral gelatine 

 it forms colonies with streamers ; the gelatine is liquefied. 

 On potatoes it forms coccus-like involution forms. Saccharose 

 solution is absolutely necessary for the production of slime. 

 The optimum lies at 25-30 C. He also found a Micro- 

 coccus gummosus, which may be distinguished from Brautigam 's- 

 species by its fermentation products. It forms yellowish 

 colonies on gelatine, but a colourless deposit on agar. The 

 optimum is at 15- 20 C. This species may produce slime 

 in saccharose and maltose solution. Schardinger has under- 

 taken a detailed enquiry into the products formed by a slime 

 bacterium, one species of which was isolated from impure 

 drinking water. It is a very short, motionless, non-sporogenous 

 bacterium which forms on gelatine a tough slimy film consisting 

 of cells linked in long chains. On saccharose or grape-sugar 

 gelatine it forms slimy and " ropy " colonies of a greyish- white 

 appearance, which when removed leave a depression in the 

 gelatine. In broth it forms slimy flakes, especially on the 

 surface, and it also makes milk viscous. In nutritive liquids 

 containing saccharose, maltose, lactose, etc., it causes fer- 

 mentation with evolution of hydrogen, and by fermentation 

 of an 8 per cent, saccharose solution, with inorganic salts and 

 calcium carbonate to neutralise the acid, it forms lactic acid, 

 acetic acid, ethyl alcohol, and succinic acid. The optimum 

 for slime formation is 20-30 C. It does not liquefy 



