132 
IOWA ACADEMY OF SCIENCES. 
CONCLUSIONS. 
Chromo^enes have interested scientists and they form a 
basis of classification. 
The organism was taken from water on the campus and 
proved to be B. violaceous laurentius. 
Oxygen is essential to growth and the production of 
color. 
It grows best in medium that contains nitrogen and in 
that medium grows rapidly. Its color characteristics de- 
pend on the environment, or medium used. 
When grown in standard solutions its action strengthens 
the conclusion that potassium phosphate is necessary for 
bacterial growth and magnesium is nesessary for the pro- 
duction of color. 
It grows well on arrowroot starch and produces an 
enzyme that reduces the starch. 
It grows in lactose solution but the other sugars seem 
to inhibit its growth. 
Long exposure to the sunlight is detrimental. 
Short exposure may be beneficial in as much as it kills 
some of the weaker organisms and thus gives a full chance 
for the stronger ones to develop. 
