ON A RED PIGMENT-FORMING ORGANISM. 409 



On a Red Pigment-forming Organism, 

 B. corallinus (?). 



By 

 Cbarleis Slater, ]9I.B.(Canta1>.). 



With Plate XXXI. 



The number of micro-organisms known which form red 

 pigments is already considerable, and include the M. prodi- 

 giosus, B. indicus, B. ruber, and B. rouge de Kiel. The 

 organism described below differs from any of these in morpho- 

 logy, cultural characteristics, and tint of pigment produced. 

 It occurred as a coral-red, slow- growing, circular, non-lique- 

 factive colony on a gelatine plate which had been used in an 

 examination of the tap water of the laboratory. As the plate 

 had been withdrawn from the moist chambers and examined 

 at least once before the colony appeared, it is impossible to say 

 whether it was derived from the water or was an air contami- 

 nation. It was most probably the latter. 



The colony was found to consist of short, thick bacilli with 

 very rounded ends. Their breadth, which is very constant, is 

 about 1 fx, and the average length of the individual cells from 

 2 to 3 /u. Very frequently two cells are joined end to end, but 

 it is unusual for more than two fully formed cells to remain in 

 apposition. The organism is motile, the movements being of 

 a rolling recurving character, with but slow motion of transla- 

 tion, except in the case of certain apparently young short cells. 

 The character of the motion recalls that of B. megaterium, 

 but is somewhat more active. The apparent curving and 



