[From The Medical News, December 31, 1887.] 
A NEW CHROMOGENIC BACILLUS-BACILLUS 
COERULEUS. 
BY ALLEN J. SMITH, M.D., 
ASSISTANT DEMONSTRATOR OF PATHOLOGY IN THE UNIVERSITY OF 
PENNSYLVANIA. 
In a cultivation of the organisms in water from 
the Schuylkill River (Belmont Reservoir), planted 
January 15, 1886, there appeared a fungus of intense 
blue color, which, on examination and further cul- 
ture, proved to be an unknown species of chromo- 
genic bacillus. 
It grows well on boiled potato at ordinary 
temperatures, with at first a beautiful dark blue hue, 
deepening into an intense blue-black, as the color- 
ing grows old. The colonies when developed fully 
are marked by numerous cup-shaped depressions 
with elevated borders. It is aerobic so far as its 
color is concerned, the cultures in the mass of gela- 
tine-peptone in tubes invariably developing as 
colorless growths, while the upper or surface part of 
the same culture shows a bluish tinge, faint because 
of the thinness of the stratum. Liquefaction of the 
surface invariably attends the cultures in peptone 
gelatine. The color of the bacillus is contained in 
the cells, and cannot be dissolved out by water or 
alcohol; nor is it affected by acids. On potato, 
1 Vide report in The Medical News, Aug. 27, 1887. 2 
SMITH , 
where the color is best seen, the bacillus foci grow 
only on the surface, not penetrating to any depth, 
as is the case with the micrococcus cyaneus. 
The bacillus, as seen under the microscope, is 
from 0.002 to 0.0025 mm. in length, and 0.0005 in 
width. It frequently develops in leptothrix-like 
chains. Some few of the individuals on the speci- 
mens mounted present a comma shape, although 
this is probably accidental, due to overheating in 
the preparation. An excellent stain for it is the 
ordinary methyl-violet. For its recognition the 
higher powers of the microscope should be em- 
ployed, although the individuals can be discovered 
with a good inch lens. 
It is possible that this form might be confused 
with bacillus syncyaneus, bacillus violaceus, or 
micrococcus cyaneus. The color, however, is so 
intense and in old colonies so dark that it alone 
should differentiate in every instance. 
The coloring matter of bacillus syncyaneus (Beit- 
rage z. Biologic d. Pflanzen, vol. iii. p. 187) is of a 
lighter shade, and is changed by soda or potash to 
a peach-blossom pink, ammonia changing it to a 
violet color-to none of which reactions the color 
of bacillus coeruleus responds. The bacillus viola- 
ceus (Ann. Societ. Nat. Moden., xiv. 1880, and 
Botanisch. Centralblatt, 1, 1528) grows best on 
solution of egg albumin, and the coloring is of a 
characteristic hue, and the color readily soluble in 
alcohol. The micrococcus cyaneus (Cohn, Schrotef} 
grows well on boiled potato, as does bacillus 
coeruleus, but penetrates with its blue color deep 
into the slice; its color is soluble in water, the 
solution at first green and later blue. This micro- 
coccus very readily produces softening and lique- 
faction, while the bacillus coeruleus produces but a A NEW CHROMOGENIC BACILLUS. 
3 
comparatively small amount of such change ; and 
microscopically the diagnosis is readily made. The 
micrococcus violaceus is distinguishable from the 
bacillus coeruleus by its characteristic hue and its 
mode of growth (in gelatinous drops of a violet 
color), and later by the microscope. 
Like the other chromogenic bacilli generally, the 
bacillus coeruleus seems to be non-pathogenic, and 
is interesting only so far as being an addition to our 
knowledge of microscopic botany. 
223 South Seventeenth St., Philadelphia.