262 BOTANICAL GAZETTE [OCTOBER 
Among the germs found in this way, I isolated several times 
during the course of the winter a micrococcus producing a 
salmon-pink pigment, which seemed not to have been previously 
described. This form first appeared in Mississippi river water, 
collected at ‘‘The Chain of Rocks,” near the St. Louis water 
tower. The water ina dilution of 1: 100° was plated in 15 acid 
gelatine and peptone agar, and in neutral Nahrstoff Heyden 
agar, using 1° of the diluted water to each plate. The micro- 
coccus developed only on the Nahrstoff Heyden plate, as it did 
in other experiments with the same water, although on one 
occasion | found it upon an ordinary agar plate, showing that the 
special medium is not essential. It also develops readily upon 
agar in pure culture. Water from other stations along the rivers 
often gave rise to pink colonies on peptone agar or Nahrstoff 
Heyden, which by casual observation could not be distinguished 
from those of the micrococcus. A closer examination, however, 
usually revealed in these cases a bacillus whose pigment upon 
cultivation showed less of a yellow tinge in the rose than that of 
the salmon-pink form. On one or two occasions these small 
pink colonies were found to be due to a yeast, but the bacillus 
was by far the more common form. The micrococcus may 
exist in other parts of the rivers, although I did not observe 
it in any other water than that of the Mississippi. My search 
for it was only incidental in connection with other work, and 
the notes upon its appearance refer it always to the locality 
mentioned, ; 
In the two cases in which the germ was isolated and culti- 
vated through all the stages, it occurred in close connection with 
a bacillus producing a yellow pigment. The first transfer from # 
rather crowded Nihrstoff Heyden plate or from the —— 
lated colony upon the peptone agar plate resulted in 4 ea 
culture of the two kinds, a second plating being necessary % 
order to separate them. The bacillus was not identified. z 
micrococcus, which it is the purpose of this paper t0 pat 
rows well and is easily cultivated at room temperature in 
