except in confirmation or contradiction of the results already ob- 

 tained. The following description of my culture B. prodi- 

 g i o s u s I , believed to be typical, will be used as a standard for 

 comparison of a series of similar forms. 



Morph ology. 



Ehrenberg described his organism as a monad. Erd- 

 mann (28), when it appeared in the cholera epidemic of 1866, 

 called it a bacillus. Schroeter (29) 1872) named it Bac- 

 terium prodigiosum, meaning by his use of the term Bac- 

 terium that it was non-motile. It was first called a Micrococcus 

 by Cohn (30) in 1872, and was known as such until Schotte- 

 lius (35) in 1887 described it as a motile rodlet. Wasserzug (37) 

 (1888) thought he could produce the coccus or the bacillus form 

 at will by growth on alkaline or acid agar. In 1896 Scheur- 

 1 e n (43) made a careful description of the morphology of B. p r o - 

 digiosus; a two day culture in neutral bouillon showed a rod 

 1,5 2 times as long as broad, with rounded ends. On the long 

 side were 24 flagella. On a two-day potato culture, the rods 

 were smaller, ellipsoid, and capsulated. Scheurlen ascribed this 

 variation to the production of unstable alkali (ammonia) by the 

 organism itself. The same thing was true for alkaline media. 

 Finally, Migula (10) (1900) adds, that the bacillus is 0,5 ji 

 broad and from 0,5 1,0 JLI long, sometimes occurring in chains of 

 26 bacilli. Motility increases and the rodlike form becomes more 

 marked in slightly acid media. Flagella are peritrichial , but vary 

 in number and length. 



Cultural features 1 ). 



Gelatin. Investigators have not differed as to the growth 

 of B. prodigiosus on gelatin and agar. On a gelatin plate 

 the growth takes place quickly ; after twentj -four hours at 20 25 C, 

 the deep colonies appear round, sharply contoured, granular and 

 gray. The surface colonies are thinner and more granular, white, 

 and round or slightly irregular on the edges. On the following 

 day the gelatin is completely liquefied, a red color appears, and 

 later the whole liquid becomes red and cloudy. 



In a vigorous gelatin stab culture a deep funnel of lique- 

 faction appears in 24 hours. Pigment appears in 48 hours, and the 

 gelatin is rapidly liquefied to the bottom of the tube and colored 

 red throughout. Usually no pellicle is formed. The rapidity of 

 liquefaction as well as of pigment production varies according to 

 the quality of the medium and the degree of vigor of the cultures. 



Agar. The character of the colonies on an agar plate is 

 quite uniform. In 24 hours the colonies appear in the depths, 

 ellipsoid, granular, and reddish. On reaching the surface they 

 spread out round, thinner, and granular, becoming bright red. The 

 color appears first in the center, and under low power the edges 

 are thin, transparent, and finely granular. The diameter reaches 

 37 mm in five days. 



1) Unless otherwise specified, observations were made at room temperature, 

 18-24 C. 



