434 MICRO-OHGANISMS IN WATER 



BACILLUS UBIQUITUS 



Authority.- -Jordan, A Re2Jort on certain Species of Bacteria observed in 

 Sewage, State Board of Health, Massachusetts, 1890, ' Purification of Sewage 

 and Water,' p. 830. 



Where Found.— Isolated from the Lawrence sewage; also found in natural 

 waters and occasionally in the air. Jordan {loc. cit.) states that this bacillus 

 resembles very closely the B. candicans isolated from soil and described by 

 Percy and G. C Frankland [loc. cit.), but differs chiefly in its power of reducing 

 nitrates, whereas the B. candicans does not. 



Microscopic Appearance.— Small short plump bacilli, closely resembling 

 micrococci, 1"1 to '2jU long and about 1 ^ broad. Very variable in form. In broth 

 cultures it exhibits a slight tendency to form short threads. It is not motile. 



Cultures.— 



Gelatine Plates. — Forms small roundish, often oval, colonies of a yellowish 

 tinge. In two days the surface colonies resemble drops of milk, being white 

 glistening projections. These centres slowly spread, become somewhat irregular, 

 and take on a dull brownish cast. Under a low power the young colonies are 

 smooth-rimmed, with a finely granular interior. No liquefaction takes place. 



Gelatine Tubes. — Produces a nail-like growth, the colour being at first a 

 lustrous porcelain white, but later a dull brownish grey. 



Agar -AGAR.- Forms a good, whitish grey growth on the surface and along 

 the inoculation line. The surface growth has a slightly metallic lustre. 



Potatoes. — Exhibits a white and restricted shining growth. 



Milk. — The milk is coagulated in eighteen hours at 37° C, and gives a strong 

 acid reaction. 



Broth.— Benders it turbid, forming a considerable flocculent deposit. On 

 old cultures a thin skin forms on the surface, but this falls to the bottom on 

 slightly jarring the tube. 



Remarks. — Reduces nitrates vigorously. (See p. 433.) 



BACILLUS SUPERPICIALIS 



LIQUEFIES GELATINE 



Authority. — Jordan, A Report on certain Species of Bacteria observed in 

 Sewage, State Board of Health, Massachusetts, 1890, ' Purification of Sewage 

 and Water,' p. 833. 



"Where Found. — Found frequently in Lawrence sewage. 



Microscopic Appearance. — Fair-sized plump bacilli, about 2*2 ^ long and 

 1 )U broad, with rounded ends. Generally occurs singly or in pairs. No spore 

 formation observed. It is motile. 



Cultures.— 



Gelatine Plates. — Under a low power the colony is nearly round, but is 

 divided by irregular lines into angular lumps, giving a somewhat cracked 

 appearance to the whole colony. The surface colonies are round, homogeneous, 

 finely granular expansions. To the naked eye the colony resembles a projecting 

 translucent drop. The gelatine is slowly liquefied, after which the colony has 

 a yellowish brown opaque centre, and a translucent edge. 



Gelatine Tubes. — Grows slowly, requiring nearly ten days to liquefy the 

 gelatine to the walls of the test-tubes. Grows almost solely on the surface, only 

 the scantiest growth appearing along the inoculation line. 



Agar-agar. — Forms a moist, lustrous, grey translucent growth. After 

 several weeks the growth is still smooth and shiny, and has assumed a light 

 brown tint. 



Potatoes. - Eefuses to grow on this medium. 



Milk. — No visible change takes place, although the reaction is slightly acid. 



Broth. — Eenders the liquid turbid very slowly. No pellicle is formed, but 

 a slight white precipitate is produced after some time. 



Bemarks. — It grows better at 37° C. than at 21° C. No reduction of the nitrates 

 obBerved. (See p. 438.) 



