1887 .] 
Dr A. B. Griffiths on Micro-Organisms. 
41 
agar-agar during an artificial cultivation of the microbe in that 
medium. The microbe stains best with gentian violet (fig. 6). I 
propose to call this microbe Bacterium allium, because it was dis- 
covered upon Allium ceg^a. 
Bacterium allium is destroyed by the reagents described under 
the head of Microeocccus prodigiosus. 
The colouring matter formed during the life-history of Bacterium 
allium is soluble in alcohol. Fig. (III.) gives the absorption 
spectrum of the pigment in alcohol. 
ABCD E&F n n 
Fig. 6a . — Absorption Spectrum of an alcoholic solution of the green pigment 
formed during the life-history of Bacterium allium. 
It will be noticed that there is an absorption band extending from 
the extreme violet to the greenish blue part of the spectrum. Also, 
an absorption band in the green and one in the yellow part of the 
spectrum. The end of the band in the yellow is exactly in the 
same position as the D Fraunhofer line in the solar spectrum. It 
will also be seen from fig. Qa that the spectrum produced by this 
pigment differs from chlorophyll, although both solutions were of 
the same intensity of colour, and nearly the same thickness, when 
placed in front of the slit of the spectroscope. 
(/) Various Micro-Organisms. 
The following micro-organisms were destroyed by the germicides 
already mentioned : — 
(1) Micrococcus citreus conglomeratus (obtained from the 
dust of the air). 
(2) Bacterium urece. 
(3) Bacterium indicum. 
(4) Micrococcus violaceus. 
(5) Sarcina aurantiaca. 
