482 MICRO-ORGAMSMS IN WATER 



BACILLUS AEBOEESCENS 



LIQUEFIES GELATINE 



Authority. — Percy and G. C. FranklancI, Zeitschrift filr Hygiene^ vol. vi. 

 p. 379. 



"Where Found. — In the rivers Thames and Lea, also in Loch Katrine water 

 and the river Dee. Identified also by Tataroff in Dorpat water {Die Dorpater 

 Wasserbacterien, 1891, p. 56) ; also by Tils in the Freiburg watfer (Zeitschrift 

 fur Hygiene, vol. ix. p. 312). ' 



Microscopic Appearance.— Slender bacillus with rounded ends, about 2*5 fi 

 long and 0*5 a* broad. Hangs together in twos and threes, but in broth cul- 

 tures forms long wavy threads. No spore formation observed. Is capable of 

 vibratory movement only. (See Plate II. 3d, 3e.) 



Cultures, — 



Gelatine Plates.— Under a low power is seen to form a thin axial stem, 

 from both ends of which root-like branches extend, which gradually assume 

 the appearance of a wheatsheaf. Slow liquefaction of the gelatine takes place, 

 and near the colony the surface of the gelatine exhibits beautiful iridescent 

 colours. (See Plate 11. 3a, 3b, 3c.) 



Gelatine Tubes. — Slowly liquefies the gelatine, producing a yellow deposit. 



Agab-agae.— Produces a dirty orange- coloured pigment, and grows slowly. 



Broth. — Benders the liquid tvirbid, and produces a yellow deposit. No pel- 

 licle forms on the surface. 



Potatoes. — Produces a luxuriant and deep orange growth. 



Remarks. — When introduced into the nitrate solution (see p. 27) no visible growth 

 takes place ; neither is any reduction of the nitrate to nitrite effected. 



BACILLUS AEEOPHILUS 



LIQUEFIES GELATINE 



Authority.— Liborius. Fliigge, Die Mlkrocn-ganismen, 1886, p. 321. 



Where Found. — In air. Mention of it in water by Boux, Analyse Microbio- 

 logique de VEau, Paris, 1892, p. 296. Also quoted by Lustig, Diagnostik der 

 Bakterien des Wassers, 1893, p. 93. 



Microscopic Appearance.— Slender bacillus with rounded ends § as broad as 

 B. subtilis ; hangs together in twos or more, often giving rise to the appearance 

 of threads. Forms bright oval spores when grown on agar-agar. 



Cultures.— 



Gelatine Plates. — Gives rise to small dots, which appear in about forty 

 hours; under the microscope they are seen to be oval, smooth-rimmed colonies 

 of a greenish yellow colour. The gelatine is rapidly liquefied, although the 

 colonies remain small and unchanged. 



Gelatine Tubes.— Forms a wide sack-like depression, the upper portion of 

 which is filled with opaque liquid of a grey yellow colour, whilst beneath it is 

 clear, containing a few isolated particles. 



Potatoes. — Forms a smooth yellow expansion having a faint shining appear- 

 ance resembling paraffin ; later the growth becomes drier near the edge, and 

 assumes an irregular and striped appearance. 



Eemarks. — It obstinately refuses to grow on any medium in the absence of air. 



