> BACTERIUM PHOSPHORESCENS. 231 



The Bacterium Hessii Guillebeau (C. B. xi, 439) is different. It 

 actively motile, liquefies gelatin, and forms no capsule. It like- 

 wise makes milk tenacious and no spores are described. In the same 

 place may be found some further statements regarding varieties which 

 render milk tenacious. Compare also Micr. Freudenreichii Guil. 

 (p. 174). 



Bacterium Pfliigeri l (Lassar) Ludwig. Bacterium 

 phosphorescens. Bernh. Fischer (Z. H. ii, 92). 



Literature. — Ludwig (C. B. 11, 372); K. B. Lehmann (C. B. v, 

 785); Beijerinck (C. B. Vill, 616, 651); Katz (C. B. IX, 157). 



Microscopically, short, plump rods, single or in pairs. Also spher- 

 ical and short oval forms occur. Striking involution forms appear in 

 old cultures. There are neither spontaneous motion nor flagella. 

 Beijerinck claims to have observed spontaneous motion in sea-water. 

 Facultative anaerobe, but does not emit light when air is excluded. 

 The addition of 3% of sea-salt is favorable. Optimum at 20°, maxi- 

 mum at about 39°, minimum at 0°. Upon gelatin and agar it is 

 indistinguishable from the Bact. acidi lactici ; once we obtained upon 

 gelatin plates colonies exactly like those in Plate 19, I, with most 

 peculiar outgrowths. Older gelatin and agar cultures exhibit a 

 tendency to become yellowish and yellowish-brown. Gelatin is never 

 liquefied. Potato cultures are yellowish, moist, sometimes with gas 

 bubbles. Grape- and milk-sugar and maltose are converted into acid, 

 accompanied by abundant formation of gas. Milk is coagulated. 



The emission of whitish, greenish light is intense if oxygen is 

 admitted as long as the cultures are frequently transferred to fresh 

 nutrient media containing salt ; but if this is omitted, the emission 

 of light is soon lost. For a time the photogenic function may be 

 regenerated by transplantation upon salt (herrings) gelatin, but it is 

 permanently lost in time if the bacteria are cultivated upon ordinary 

 media with infrequent transfer. Concerning the photogenesis, com- 

 pare page 57. A few drops of phosphorescent bouillon culture may 

 give a milky luster to a liter of sea-water. 



Neither the bacterium nor its metabolic products in small amounts 

 are harmful. It lives in the northern seas, causes occasionally phos- 

 phorescent sea, more often phosphorescence of fish, meat, etc. 



The Bacterium of Giard (C. B. VI, 645 ; vin, 177), which is 

 pathogenic for crawfish, and makes the living, inoculated animal 

 phosphorescent, appears, from the incomplete description, to be simi- 

 lar. Phosphorescent gnats (mycetophila), observed as rarities in 

 Germany, must owe this property to bacteria. Henneberg (C. B. 

 xxv, 649). The phosphorescent bacillus described as Photobacte- 

 rium javanicum Eykmann (C. B. IX, 656) is plump and motile. 

 Regarding a second group of photogenic micro-organisms, see under 

 Vibrio albensis Lehm. and Neum. 



1 Beijerinck distinguished B. phosphorescens from B. Pfliigeri by 

 biologic characteristics. 



