412 CHARLES SLATER. 



the reddish solution simply cutting oflF the blue end of the 

 spectrum. 



The production of the pigment is unaffected by light, 

 taking place as well in the dark as in diffused light. 



The pigment-producing power is remarkably constant, and 

 in no case have any colourless colonies been obtained when 

 free access of air is possible. In stab cultures, and in the 

 depths of liquid media, the colour is absent. 



If recent cultures of the organism on gelatine or potato 

 are examined, the growth is found to consist chiefly of cells 

 scarcely twice as long as broad, and so rounded at the ends 

 as to appear oval. These small cells are actively motile, and 

 the protoplasm appears to be collected as a refringent mass at 

 each pole. These cells are not unfrequently united in pairs, 

 connected by a thin filament. The bicellular organisms are 

 actively motile, and present the appearance of a flagellated 

 organism. They are especially noticeable in bouillon cultures. 

 Besides those two forms which seem to be characteristic of 

 young and active growth, there occur cells which are three 

 to four times as long as broad, some showing signs of division 

 into the bicellular stage, and others no trace of this separa- 

 tion. 



The organism increases by fission, which is somewhat slow, 

 a cell dividing at the temperature of 15° C. in about twelve 

 hours. The most noticeable feature in this organism at what- 

 ever stage examined is, as mentioned above, the irregular 

 refractive power of its protoplasm, and its tendency to collect 

 in masses, having various positions in the organism, but very 

 frequently to be found at the poles of the cells. Stained 

 specimens present, also, a very great variety of appearances, 

 owing to their extremely irregular staining. A stained pre- 

 paration of this bacillus recalls, very strongly, a culture of the 

 Bacillus typhosus when in the condition which shows the 

 '' clear space '' and the so-called spores, and the appearances 

 presented by this pigment-forming organism are not without 

 interest when compared with those of the pathogenic microbe. 

 Certain cells show, both when stained and unstained, caps of 



