112 DETERMINATION OF SPECIES. 
(4) Not distinctly pathogenic to pigeons. 
CHOLERA GROUP. 
Msp. comma type. 
B. Do not produce indol, or very little, at 
least after twenty-four hours. 
CHOLERA-NOSTRAS GROUP. 
Msp. finkleri type. 
IV. CLASSIFICATION OF WATER BACTERIA BY 
GROUPS. 
Fuller and Johnson have applied the group 
method of classification to the bacteria of water as 
follows :! 
WATER BACTERIA. 
I. Fluorescent. Group I. 
II. Non-fluorescent. 
1. Chromogenic. 
A. Red. Group II. 
B. Orange. Group III. 
C. Yellow. Group IV. 
D. Violet. Group V. 
2. Non-chromogenic. 
A. Gelatin liquefied. 
(a) Characteristic colo- 
nies on gelatin 
plates. 
1 Jour. of Exp. Med., vol. iv., Nos. 5-6, p. 609. Conn 
has adopted a somewhat similar classification into groups 
for the dairy bacteria. See Report of the Storrs (Connecti- 
cut) Agricultural Experiment Station for 1899. 
