( 1070 ) 
The very dark colour of the pigment in an aerated alkaline medium 
makes it easy to detect the quereite bacterium. If for example, on 
a broth agar plate with 0.5 proc. quercite, some drops of sewage 
water are spread, there is much chance that after one or two days 
at 30°C. some colonies appear that are jet-black, or lie amid a black 
diffusion field, distributed among the numerous non-pigment producing 
colonies, which latter are little troublesome, excepting B. jlworescens 
liquefaciens, whose secretion is injurious to the quercite bacteria. 
In a previous paper I alluded to a simple experiment whereby 
aromatic milk results *). 
To this end milk should be kept at a relatively low temperature, 
for example at 15° to 20° C., with full admission of air, so that 
it is left to spontaneous corruption by the aerobie germs it contains. 
The acidification is at first feeble on account of the low tempera- 
ture, but it is then that the “aroma bacteria” increase very much 
and produce the characteristic ester which has not yet been nearer 
examined. 
If of such aromatic milk streaks are made on a quereite plate 
of the above composition a large number of brown colonies of 
quercite bacteria appear after 2>< 24 hours at 30° C. An examination 
of their faculty of producing the aroma in milk proves that it does 
exist but only in a slight degree. The real “aroma bacteria’, which 
develop by the side of the “quercite colonies” and correspond with these 
in all other respects, do not possess the power of producing pyrogallol 
from quercite, hence, though belonging to the same species, they 
represent other varieties. The quercite bacterium might thus be named 
P. aromatica var. quercito-pyrogalhica. That P. aromatica is so easily 
distinguished as a species, makes it in this case possible to indicate a 
character by means of which forms found in nature and seemingly alike, 
may be recognised as belonging to different varieties. The oxidation 
function here, thus proves to be very variable, being present or 
S. 584, 1902. — B. butyri aromafaciens Kerra, Bacillus N°, 41 Conn ; Pseudomonas 
fragariae Grouper, Centralbl. f. Bact. 2te Abt. Bd. 9, p. 705, 1902. — Ps. fragariae 
Gruser, Id. Bd. 14, p. 122, 1905, and Ps. fragaroidea Hararp Huss. id. Bd. 19, 
p. 661, 1907. — Perhaps likewise the yellow-coloured Ps. trifolii of Haratp Huss, 
ld, Bd. 49, p. 68 and 149, 1907, and several other different forms less easily 
recognisable in the literature are synonyms. — Bacillus esterificans Maassen, Arbeiten 
des Kais. Gesundheitamtes, Bd. 15, 1899, is quite another species, producing spores 
and belonging to the hay bacilli, and thus related with Granulobacter polymyxa 
PRAZMOWSKI. 
1) Kermentation lactique dans le lait. Archives Neérlandaises, Sér. IL T, 13, 
p. 350, 1907. 
