TOXINS 



201 



FIG. 114 



at one end. After long-continued culture on artificial media the 

 flagellum may be lost, but it reappears after inoculation into an 

 animal. It does not form spores. It stains well with the watery 

 anilin dyes, but is Gram negative. 



Cultural and Biologic Properties. The Bacillus pyocyaneus grows 

 well at room and incubator temperature. On gelatin plates small 

 yellowish-white colonies appear first in the deeper parts and extend 

 rapidly toward the surface, where they then show a dark yellow centre 

 and a periphery with radial striation. The medium itself assumes 

 a typical greenish fluorescent tint around the colonies. The gelatin 

 is liquefied and the culture sinks to the bottom, forming a slimy red- 

 brownish mass. In gelatin stick 

 cultures liquefaction first appears 

 at the surface in a funnel-shaped 

 manner, and then rapidly spreads 

 downward. On agar slants kept 

 at incubator temperature the 

 growth is rapid, and the green 

 pigment generally turns brownish 

 after two days, t spreading succes- 

 sively through the entire culture 

 medium. Pigment formation oc- 

 curs only in the presence of 

 oxygen, and the liveliest colors 

 are formed at room, but not at 

 incubator, temperatures. The 

 bacillus not infrequently produces 

 a blue or even from the begin- 

 ning a greenish-brown pigment 

 instead of a decided green color. 



In bouillon the bacillus grows well. A white ring first shows at the 

 margin of the free surface, and from it a complete pellicle is formed. 

 From the latter a green zone extends downward into the medium. 

 After two weeks the whole growth sinks to the bottom and forms 

 a slimy sediment. After many weeks in the incubator the formation 

 of an autolytic ferment causes the growth to undergo self -digestion. 

 Milk is coagulated by the bacillus. The organism grows well on 

 potatoes, and forms first a grayish-brown and later on a yellowish- 

 green pigment, which is composed of two constituent bodies. One of 

 these, known as pyocyanin, is bluish green and soluble in chloroform, 

 the other is greenish, fluorescent, and insoluble in chloroform or 

 alcohol, but soluble in water. Pyocyanin is originally a colorless sub- 

 stance, and obtains its color only after subsequent oxidation. 



Toxins. The Bacillus pyocyaneus is pathogenic in experimental 

 inoculation for guinea-pigs and goats; rabbits, mice, and pigeons are 

 slightly susceptible. Wassermann has shown that the pathogenic effect 

 of the organism upon man and animals depends upon a soluble toxin 

 and an insoluble endotoxin. 



Bacillus pyocyaneus. X 1000. (Author's 

 preparation.) 



