220 IMPOBTANT VARIETIES OF FISSION-FUNGI. 



Bacterium acidi lactici. Hiippe. 



(Plate 14.) 



Literature. — Hiippe, Mitteil, aus dem Gesundheitsamt li, 309. More 

 recent literature up to 1891 is given bySeholl ; Die Milch (Wiesbaden, 

 1891). Compare also Kayser (A. P., 1894, p. 737), where there are 

 described 15 organisms which produce lactic acid. 



Microscopic Appearance. — Short, somewhat oval rods 

 (0.6-2 iJ. long, 0.4-0.6 ij. broad), usually in pairs, rarely in 

 longer chains (14, ix). 



Motility and flagella are absent. 



Staining Properties. — Stain by Gram's method, but 

 not very well. 



Requirements as to Nutrient Media and Temper- 

 ature. — Grows abundantly at room and incubator temi:)er- 

 ature upon the various nutrient media. It grows better 

 aerobically, and not at all deep in shake cultures prepared 

 from non-saccharine media, ^^^ith the addition of sugar, it 

 grows well anaeroljically. 



Growth upon Gelatin and Agar. — Not essentially 

 different from Bact. coli, very abundant, especially upon 

 agar, and moist and slimy. Upon gelatin, delicate. In 

 thin plate, the colonies may become 5-10 mm. in diameter 

 (14, V). 



Bouillon Culture. — Diffuse cloudiness, abundant sedi- 

 ment. 



Potato Culture. — Somewhat widely spreading, wavy, 

 smooth-edged growth, somewhat elevated, at first grayish- 

 to yellowish- white, later sometimes brownish-yellow. After 

 longer standing, bubbles arise which often are strongly 

 refractive, and later may burst (14, x). 



Milk Culture. — Compact coagulation, with expression 

 of clear serum ; a few little gas bubbles are always 

 present. 



Chemical Activities. — It forms from grape- and milk- 

 sugar a mixture of lactic and acetic acids, and sometimes 

 traces of alcohol, together with an abundance of gas. The 

 lactic acid may be optically inactive fermentation lactic 

 acid, but so far special investigations are lacking. As first 

 observed by Hiippe, the powers of producing lactic acid 



