74 Ward . — ^4 Violet Bacillus from the Thames . 
regained more and more on transference. In some cases, 
however, the non-pigmented variety appeared on normal 
plates, and I was quite unable to refer it to any cause. 
This white variety would probably repay further study. 
In any case I think the evidence is against the multiplicity 
of species of violet Bacteria which now exist in the literature. 
At the same time, the difficulties of microscopic cultures of 
the present form, and the lack of information regarding them 
in other alleged ‘ species ’ or forms, should make us hesitate 
before we decide as to the autonomy of any, since it may be 
taken as certain that we do not know the whole life-cycle of 
even a single member of this type. 
EXPLANATION OF FIGURES IN PLATE VI. 
Illustrating Professor Ward’s paper on a violet Bacillus. 
Fig. i. Rodlets from fresh gelatine ( a ) not stained ; (b) similar rodlets stained 
with methylene-blue — the ends often stain more deeply than the centre. 
Fig. 2. Rodlets, &c., from an old Agar culture (a) stained with methyl-violet ; 
(b) similar preparation from old gelatine-cultures showing ‘ involution-forms.’ 
Fig. 3. Rods and filaments from a twenty-four hours’ broth-culture. 
Fig. 4. Plate-colonies on gelatine after ten days’ growth at 20°C., from a culture 
a year old (nat. size). 
Fig. 5. Plate-colonies in various stages of development on gelatine : (a) after 
twenty-four hours at i8° C. ; (b) the same on third day; ( c ) submerged colonies on 
fourth day at i8° C. All under i obj. 
Fig. 6. Plate-colonies: (a) after ten days at i8°C., nat. size, showing develop- 
ment of pigment, and liquefaction ; (b) the non-pigmented variety after three 
weeks at i8° C. ; the plate is liquefied, and cream-coloured or yellowish colonies 
are floating in the liquid. 
Fig. 7. Stab-cultures in gelatine : (a) after three days; (b) after ten days, lique- 
faction is beginning, but the colonies are still white ; ( c ) after eighteen days, the 
violet pigment appearing in the funnel ; (d) after a month, the gelatine liquefied 
some way down. All at ordinary temperatures. 
Fig. 8. Gelatine-streak after ten days at 15° C. ; the purple growth lies in 
a groove of liquefaction. 
Fig. 9. Agar-culture at 20° C. ; (a) after four days, the purple colour appearing 
in the white, and ( b ) on the tenth day, the white nearly all gone. 
Fig. 10. Potato-culture, ten days at 20° C., the purple hue has only invaded 
part of the growth — the rest remains dirty brown in colour. 
