Ward . — Some Thames Bacteria . 293 
Jacksch’s liquid. Slow growth and greasy flecks, falling as a very white deposit. 
Better at 25 0 than at 35 0 . No odour. 
Pathogenicity. Not pathogenic to guinea pigs, according to Professor Kanthack’s 
report l . 
After remaining from May 28 to June 8 of the following 
year, i. e. over twelve months, it was found quite easy to 
revive this form from an agar tube. Good plate-cultures 
resulted in four days at 20-22° C., and the colonies were quite 
characteristic. Further cultures in gelatine, agar, potato, 
broth and milk tubes confirmed this, and the results at 25° 
and 35° respectively were as above. 
This form must therefore be regarded as a very constant 
and persistent one, in marked contrast to many of the others 
I have had to deal with. 
II. A colourless capsuled Coccus or Bacterium 2 . (PI. XX.) 
An interesting form, isolated and cultivated through all 
stages at least twice from the river in the autumn, was one 
which occurred on the plates as small, short, oval, non-motile 
rodlets over 1 n long by 0-75 to 1 /x broad, and invested by 
a tough dense zoogloea or capsule, which occurred round the 
groups of dividing rodlets — then biscuit-shaped — as well as 
round individual cocci or rods. 
If rapidly stained by Gram’s method the capsules are 
decolourized, and the rodlets coloured : but they are easily 
decolourized. The stained rods = 1 x o«6 n to cocci about 
o*6 fji. The capsule = about 6 to 10 ju. 
On plates at 12-15° C. the colonies are white, porcellanous, 
shining discs or fronds, with a central spot and faintly 
zoned. To the unaided eye the colonies look bluish-white 
and translucent if held up, the zone or zones appearing 
yellower : the zones sinuate in agreement with the indented 
1 I have to thank my colleague, Professor Kanthack, for kindly examining 
a number of these bacteria for me in respect of their pathogenic properties. 
2 Referred to as the type of Group XI in Proc. R. S., Vol. xli, p. 420. 
X 
