208 SPECIAL BACTERIOLOGY 



2. Nutrient Gelatine is Liquefied, 

 (a.) CHROMOGENIC. 



Bacillus Arborescens. Slender bacilli, frequently forming wavy 

 threads ; non-motile ; distinguished by the branch-like ramifications and 

 iridescence of the colonies in gelatine plate cultures. 



On Potatoes it forms a yellow to yellowish-red pigment. 



Bacillus Pluorescens Liquefaciens. A motile bacillus, very like 

 the Bacillus pyocyaneus. It liquefies the gelatine very quickly, with the 

 formation of a greenish-yellow pigment, brightly fluorescent. 



On Glycerine Agar the cultures are quite typical, exhibiting an olive- 

 green to olive-brown colour. 



Bacillus Rubidus. Medium-sized, strongly-motile rods, arranged 

 in long threads ; a brownish-red pigment is produced in gelatine agar 

 and potatoe cultures ; except the formation of pigment it has scarcely 

 any other characteristic. 



Bacillus Violaceus. Small, slender, strongly-motile rods, forming 

 spores in the middle of the rods in agar cultures. Cultures on gelatine 

 exhibit in the liquid portions a bluish violet-coloured bacterial mass. 

 On agar and potatoe media, the formation of the pigment is very 

 abundant, varying from a dark violet to an almost black colour. 



Bacillus Viscosus. A bacillus very like the Bacillus fluorescens 

 liquefaciens, but distinguished by forming a chocolate-coloured coating 

 on the media. 



Bacillus lanthinus. Medium-sized motile bacilli ; the appearance 

 of a colony growing on a gelatine plate culture is compared to a drop 

 of ink. It forms on all media a violet pigment. 



Bacillus Helvolus. Motile rods of varying length, sometimes 

 arranged in shorter threads, producing a yellow to sulphur yellow- 

 coloured pigment. On plate cultures the colonies appear as circular 

 bright yellow discs lying in a funnel-shaped liquefied cavity. On agar 

 media an extensive coating of an intense yellow colour is formed. 



Bacillus Prodigiosus. Very small rods (formerly described as the 

 Micrococcus prodigiosus, or Monas prodigiosa) often arranged in small 

 chains, possessing very slight motility. It is found in the air, less often 

 in water, frequently found in starch - containing media (bread and 

 potatoes), in meat, and in milk. 



It grows on all the media, producing a bright red colour, which is 

 most intense on potatoes, exhibiting a blood-red coloured layer. 



On Gelatine Plates the deep colonies are like white points, while the 

 surface colonies are round and red in colour, with irregular borders. 



