482 MICRO-ORGANISMS IX WATER 



BACILLUS ARBORESCENS 



I LIQUEFIES GELATINE 



Authority. Percy and G. C. Frankland, Zcitsclirift 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 

 Wasscrbactericn, 1891, p. 50) ; also by Tils in the Freiburg water (Zeitschrift 

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



Microscopic Appearance. Slender bacillus with rounded ends, about 2-5 /m 

 long and 0-5 n 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. 3u, 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 II. 3A, 3, 3c.) 



GELATINE TUBES. Slowly liquefies the gelatine, producing a yellow deposit. 



AGAB-AGAR. Produces a dirty orange-coloured pigment, and grows slowly. 



BROTH. Renders the liquid turbid, and produces a yellow deposit. No pel- 

 licle forms on the surface. 



POTATOES. Produces a luxuriant arul deep orange growth. 



Remarks. When introduced into the nitrate solution (seep. 27) no visible growth 

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



. BACILLUS AEKOPHILUS 



I LIQUEFIES GELATINE 



Authority.' Liborius. Fliigge, Die Mikro&rganismen, 1886, p. 321. 



"Where Found. In air. Mention of it in water by Roux, Analyse Microbio- 

 logiqvc cle VEaii, Paris, 1892, p. 290. Also quoted by Lustig, Diagnostik dcr 

 Baktenen dcs Wassers, 1893, p. 93. 



Microscopic Appearance. Slender bacillus with rounded ends g as broad as 

 B. siibtilis ; 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. 



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



