!66 BACTERIOLOGY 



115. Bact. caudatum (Wright) 



B. caudatus Wright : I.e., 444. 



Morphology. Bacilli small, slender, with conical ends ; in pairs and as filaments. 

 Gelatin colonies. In 3-4 days, colonies 1-2 mm., yellow, translucent, smooth 



wavy; microscopically, with a yellowish centre and a somewhat radiate, 



light periphery. 

 Gelatin stab. In depth, growth villous ; on the surface, liquefaction crateri- 



form. with yellowish flocculi. 



Agar slant. Growth, yel]ow^glLstening, translucent, slightly spreading. 

 Bouillon. Turbid, with a yellowish sediment. 

 Potato. Growth dark yellow, elevated, spreading ; surface uneven. 

 Litmus milk. Slightly decolorized. 



Glucose bouillon. No gas. Indol } reaction doubtful. No growth at 36 C. 

 Habitat. Water. 



1 1 6. Bact. Kralii 



B. fuscus-liquefaciens Dyar : I.e., 376. 



Morphology. Bacilli 0.5-0.6: 1.0-2.0 /u.; occur singly and in short chains. 

 Gelatin. Slowly liquefied, i.e. after 14-50 days. 

 Agar slant. Growth bright orange, forming a crusty membrane. Nitrates 



slightly reduced. 

 Litmus milk. Blue. 

 Habitat. Air (from Krai's laboratory). 



117. Bact. helvolum (Zimmerman) 



B. helvotus Zimmerman : Bakt. Nutz u. Trinkwasser, 1890. Dyar : I.e. 



Morphology. Bacilli 0.5 : 1.5-2.5-4.5 /u,. Optimum temperature 25 C. 



Gelatin stab. Slight growth in depth ; on the surface, growth convex, becom- 

 ing spreading, and Naples yellow in color ; later, a crateriform liquefaction. 



Agar slant. Growth of a Naples yellow color. 



Potato. Growth yellow, becoming slightly greenish. 



(Gelatin. Liquefied in 30-40 days. Reduction of nitrates variable. Milk. 

 Not coagulated. Litmus milk. Blue.) Dyar. 



Habitat. Water, air. 



1 1 8. Bact. plicatum (Zimmerman) 



B. plicatus Zimmerman : I.e. 



Morphology. Bacilli small, slender; in twos or short chains. Optimum tem- 

 perature 20 C. 

 Gelatin colonies. Yellowish white, irregular ; microscopically, rough, moruloid. 



