500 MICRO-ORGANISMS IN WATER 



MICROCOCCUS CREMOIDES 



LIQUEFIES GELATINE 



Authority. — Zimmermann, Die BaJcterien unserer Isfutz- und Trinkwdsser, 

 insbesondere des Wassers der Ghemnitzer Wasserleitung, Chemnitz, 1890. 



Where Found. — In the Chemnitz water supply. 



Microscopic Appearance.— Cocci about 0-8 fi in diameter, grouped together 

 like a bunch of grapes. Not motile. 



Cultures. — 



Gelatine Plates. — In the depth small yellowish white dots arevisible. Under 

 a low power they are circular discs, smooth -rimmed, and with yellowish or 

 greyish brown granular contents. On reaching the surface the contour becomes 

 lobular and denticulated, and the gelatine becomes liquid in a saucer-like depres- 

 sion. The yellowish white colony covers the bottom of the depression, and 

 becomes arranged in concentric rings. Under a low power such colonies con- 

 sist of brownish yellow granular aggregates, surrounded by a less dense granu- 

 lar circle, which is enclosed by a transparent liquid zone in which granular 

 particles are scattered here and there. From the periphery delicate and 

 radial extensions often stretch into the adjacent gelatine. 



Gelatine Tubes. — In from three to four days the path of the needle in tbe 

 depth is liquefied, whilst on the surface a bubble of gas is usually present,, 

 beneath which yellowish white masses of bacterial growth collect, and lower 

 down the liquid is clear or contains but a few granular particles, whilst the bot- 

 tom of the funnel again is filled with the yellowish white growths. After 

 from six to seven days a yellowish white pellicle floats on the surface of the 

 liquid gelatine. 



Ag-ae-agak. — Forms a yellowish white amber-like shining expansion, which 

 is irregular and lobular at the periphery, and granulated on the surface. 



Potatoes. — Grows abundantly, producing a raised cream-coloured expansion. 



Bemarks. — It will not grow in the absence of oxygen. 



MICEOCOCCUS FEEYIDOSUS 



Authority. — Adametz, Die Bakterien der Nuts- iind Triiikwdsser, Vienna, 

 1888. 



Where Found.— In water. 



Microscopic Appearance. — Small round cocci 0*6 fi in diameter; occurs as 

 diplococci, also in small groups. Not motile. 



Cultures.— 



Gelatine Plates. — The depth colonies appear as small white dots after from 

 four to five days. Under a low power they are faint yellow in colour, highly re- 

 fracting, smooth-rimmed, and resemble drops of dew. The surface colonies, after 

 from five to six days, are transparent and yellow, with a serrated edge and nume- 

 rous indentations and lobular projections. In older colonies the centre is granular 

 and brownish in colour, whilst the yellowish growth surrounding it exhibits a 

 sHght folded appearance. No liquefaction takes place. 



Gelatine Tubes. — Forms a very thin surface expansion, circular, and finely 

 serrated, whilst a granular growth appears in the depth. 



Glycerine-gelatine. — Gives rise to numerous bubbles of gas all along the 

 needle's path in the depth. 



Agae-agar. — Forms a circular milk-white slimy expansion which exhibits 

 later a mother-of-pearl iridescence. 



Potatoes. — Produces a dirty white irregular expansion. 



Eemarks. — In cane, grape, and milk-sugar solutions respectively it develops 

 slowly, causing a slight turbidity (Tils). 



