72 Ward. — A Violet Bacillus from the Thames. 
Zopf’s Bacterium janthinum differs in some characters — 
size, milk-cultures, &c. — but might very well pass for a feeble 
form of mine in other respects. Lustig 1 regards Zopf’s form 
as identical with the one found by Bujwid in hail, and agrees 
with Jordan 2 that it is the same as one previously found by 
Hueppe. Jordan also points out the resemblances between 
Zopf’s form and Rosenberg’s Bacterium h. 3 , as well as the 
doubts as to what the latter is — possibly identical with Frank- 
land’s B. violaceus or with Jordan’s B. violaceus Laurentius. 
Zopf’s B. janthinum has been found often in water, e. g. by 
Plagge and Proskauer 4 , Roszahegyi 6 , Jordan 6 , &c. The latter 
also discusses the difference between the three forms last 
mentioned. 
As regards Smith’s B. coeruleus , from the Schuylkill, if the 
colouring-matter is really formed in the cells, as stated, and is 
insoluble in alcohol, there is no doubt a sufficient difference ; 
moreover, the pigment is a blue one, and we may safely regard 
this as a distinct form on the evidence to hand. 
Claessens’ B. berolinsis indicus , from the Spree, also pro- 
duces a blue (indigo) pigment, insoluble in alcohol, and many 
other differences exist, in addition to its not liquefying the 
gelatine and not rendering broth turbid 7 , which suffice to 
distinguish it. 
Voges’ B. coeruleus is too stout and short for my form, and 
again the pigment is a different colour — blue, not violet — and 
does not form in broth. The agar- and milk-cultures are 
also decidedly different. Moreover, the colour is soluble in 
water. There can be no doubt this form is quite different 
from the one I have isolated from the Thames. 
Voges’ B. indigoferus is still more different, and especially 
in its minute size. 
There remains Eisenberg’s B. membranaceus amethystinus. 
The differences between this form and mine are so few and 
1 Diagnostik del* Bakterien des Wassers, 1893, p. 76. 2 1 . c., p. 841. 
3 Ueber die Bakterien des Main-wassers, Arch. f. Hyg., Bd. v, p. 458. 
4 Zeitschr. f. Hyg., Bd. ii, p. 458. 5 Lustig, 1 . c., p. 76. 
6 1 . c., p. 840. 7 According to Voges, 1 . c., p. 302. 
