( 156 ) 
surprising. All liquefying colonies, and most flnorescents have disap- 
peared, whereas, among two common and some less frequently 
occurring species, B. stutzeri developes in great numbers and is easily 
recognised by the characteristic properties of its colonies. 
By repeating the said transport this bacterium may still be more 
multiplied, so that, after three or four successive inoculations, practic- 
ally a pure culture of this species is obtained. 
From soil of the garden of the Bacteriological Laboratory I regularly 
obtained the same bacterium, in the course of the winter of 1901—2 
by applying the “bottle method” with this liquid: 
Tap-water, 2 °/, calcium-malate, 1 °/, KNO, and 0,05 °/, K,HPO,,. 
In the spring, however, though there were constantly some colonies 
of the species, the number of its germs proved so small that they 
were replaced by other denitrifying bacteria, particularly B. denitro- 
fluorescens, of which more presently. 
A detailed description of B. stutzeri is given by Burri and Sturzer 
(l.c.), as well as KÜNNEMANN (l.c). It will therefore be sufficient 
here to give the chief characteristics by which this species is directly 
recognised. 
The bacterium is a short, thick rodlet with a peculiar vibrio-like 
motion. 
The colonies on gelatin are extremely characteristic (see Plate). After 
three or four days they have a diameter of about 0.5 mm. and after a 
week they attain 1 to 1.5 mm. When magnified they then resemble 
a rosette, or have an irregularly folded or crispate, greyish surface. 
The peculiar structure appears only distinctly, when the glass-dish 
which contains the plate culture, is reversed and the colony is seen 
through the bottom with about a 30-fold magnification. The most 
frequent shapes are represented in figures 1—4. 
But it may happen that the crispate character becomes still more 
conspicuous and then the image is as in fig. 5. 
Commonly it seems as if regularly arranged smaller colonies are 
situated in the larger ones, which may often be observed till in 
the outer border, and points to a peculiar periodicity of the mucus 
secretion in the interior of the colony. 
In the colonies moreover a fine deposit is observed, and sometimes 
very distinct crystals, which may also be found in the gelatin around. 
All these characteristics are particularly marked when the cultures 
have been recently isolated, but they may in the course of time get 
lost or become indistinct. Another property however remains always 
quite distinct, i.e. the adhering to the gelatin. Young colonies can only 
be removed in one piece, and of the older always part remains behind. 
