236 BACTERIA. 
Unlike B. aurantiacum, the surface is soon wrinkled 
and covered with a fine network of ridges. The color 
then rapidly changes, first to a light then to a dark 
brown with a reddish tinge; the latter color is per- 
sistent. The cells are .385-.54 by .8-384. They may be 
single or in filaments of two to several. In the old 
zoogloea, the cells are much shorter—almost spherical. 
Bacterium syncyanum, Schriter; Vibrio syncya- 
nus, Ehrt. Some milk exposed to the air for sev- 
eral days, developed a luxuriant growth from one 
to two millimeters thick, of a deep blue color. The 
zoogloea was found to consist of slender bacteria which 
presumably belong to the above species, but for want 
of adequate descriptions, it ceuld not be identified 
with certainty. | 
A blue form having similar cells, developed on the 
under side of a potato touched to the wall in a barn. 
Little groups of minute dots multiplied for three days 
with considerable rapidity, but growths of other species 
soon gained the ascendency and every attempt at culture 
was unsuccessful. AS a consequence the species was 
soon lost. I have very little hesitation in referring the 
growth to the B. syncyanum. 
Bacterium violaceum, Bergonzini. Glairy growths of 
violet zoogloea appeared at three different times, but 
always in connection with B. dutewm or other species 
whose growth is rapid. I never succeeded in getting an 
absolutely pure culture, but at one time [had the species 
growing quite luxuriantly for about two weeks. It al- 
ways developed on the under side of a culture, and I 
found it grew much better if covered with a thick cup 
which completely excluded the light. 
While working in the botanic garden in Cambridge, 
I was given material for a culture of this species by 
Prof. Trelease, who received it from Prof. Farlow, in 
120 
