IOWA ACADEMY OF SCIENCES. 
139 
obtained frequently from butter and milk, but the organism 
undoubtedly came from the air. 
N. aurantiaca Flligge. — This organism is also quite commonly 
met, and appears on gelatin and agar plates exposed to the air. 
Bacillus jluorescens Uqaefaciens Flligge. — This common inhab- 
itant of water also 'occurs on potato, milk and butter. Scarcely 
a sample of water can be plated without obtaining this 
organism. 
B. 'pyocxjaneus Gessard. — This has been obtained several times 
from wounds and Dr. S. Whitbeck obtained a pure culture in 
open synovial bursa. Inoculation into the peritoneal cavity was 
followed by death in forty-eight hours. In old cultures there 
is a gradual tendency for the organism to lose its power of 
forming coloring matter. Gessard"^ has isolated two pigments a 
fluorescent green and a blue, the latter called pycoyanin. 
Bacillus prodigionsus Ehrenberg. — This species is well known 
to most bacteriologists. It has long attracted attention because 
of the red stains produced on potatoes, boiled bread, and the 
red color it imparts to milk. According to several investi- 
gators this organism is not a native to this country. 
The species is however, recorded at Ames by Bessey. He 
commonly obtained a red organism on sliced potatoes exposed 
to the air. 
There are of course several red organisms and as the organ- 
ism was reported before the era of modern bacteriological 
methods I must therefore express some doubt as to the correct 
determination of the Bacillus prodigiosus found by Bessey. 
The senior writer has at various times had cultures of this 
organism in the laboratory. Thus we had good growing cul- 
tures in 1889, 1892, but all attempts to make old cultures failed. 
In 1894 a blood-red colony came up in culture plate. Cultures 
of this organism had never been in this laboratory so far as we 
know. In the spring we had received from Dr. Irving W. 
Smith, cultures of several species obtained from the laboratory 
of Johns Hopkins University. The cultures appeared pure 
but they may have been contaminated. The senior writer 
observed this organism on one other occasion in the botanical 
laboratory of the Shaw School of Botany, St. Louis. Cultures 
of B. prodigiosus were obtained from rotting sweet potatoes, 
but European cultures were common at the time in the labora- 
5Gessard. De la pyocyanine et de son Microbe. These de Paris, 1882. Nouvelles 
recherches sur la Microbe pyocyanique. Ann. d VInstitut Pasteur. Vol. IV, 1890, p. 89 
6Bull. Dept, of Botany, Nov. 1884. 
