CINCINNATI PROCEDURE 313 
hours at 37° C., the result is considered negative, and 2. colt is recorded as not 
present. If gas is formed the result is considered positive for B. coli, subject to 
the results of the gelatin transplant and a microscopical examination. If after 
forty-eight hours’ incubation at 37° C. the gelatin transplant will solidify on 
cooling, the culture is considered as non-liquefying. If the gelatin does not 
solidify on cooling, and gas is formed in the lactose broth transplant and the 
microscopical examination demonstrates a bacillus, the organism is called B. 
cloace and included in the B. colt numerical estimation as it has the same sani- 
tary significance. 
The microscopical examination consists of a smear made according to the 
method of Gram from the Endo plate colony selected for transplanting. A 
Varying Quantities (0.01-0.1-1.0 ¢ c.ete ) 
Planted into 
Lactose Broth 
Gas Formation-Presumptive Positive 
Smallest Quantity giving gas 
Sterile Plate 
Negative 
is Plated on Endo’s Medium | 
Typical or Atypical Colony 
Fished and Planted into 
Lactose Broth 
B 
No Gas Formed 
Negative 
Liquefaction 
X Negative 
Non- 
Liquefaction 
A-~- Bacillus 
Gram-negative 
Non-spore former 
Microscopical 
Examination 
Not A-~ Bacillus 
Gram-negative 
Non-spore former 
Negative 
B, Coli-Confirmed 
Method Followed at Cincinnati Plant for Identification of B. coli. 
Gram negative non-spore-forming bacillus obtained following the above pro- 
cedure fulfills in every particular the definition for the Bacillus coli. If other 
than a gram-negative non-spore-forming bacillus is obtained, it is not considered 
B. cole and is so recorded, but such a result is unlikely and has not been en- 
countered in experiences at Cincinnati. The liquefaction of gelatin and dis- 
cordant results in the microscopical examination accompanying gas production 
in the lactose broth transplant are likely to be due to mixed cultures, in which 
case'separation should be made by replating from the lactose broth transplant. 
“Estimation of the B. colt index is made according to Phelps’ method 
—that is, the reciprocal of the smallest volume of water which gave a positive 
test is taken as the approximate number of B. colt per cubic centimeter and is 
recorded as such. In case of an anomaly it is assumed that the positive result 
should have been negative and the negative result positive and is so considered 
