lin peptone solution.
Dextrin peptone solution.

17. Differentiate the bacilli after isolation by means of their cultural
reactions and biological characters into members of:

I. The Escherich Group.

B. coli communis.
B. coli communior.
B. lactis aerogenes.
B. cloacae.

II. The Gaertner Group.

Bacillus enteritidis (of Gaertner).
B. paratyphosus A.
B. paratyphosus B.
Bacillus cholerae suum.

III. The Eberth Group.

B. typhosus.
B. dysenteriae (Shiga).
B. dysenteriae (Flexner).
B. faecalis alcaligines.

18. Confirm these results by testing the organisms isolated against
specific agglutinating sera obtained from experimentally inoculated
animals.

If a positive result is obtained when using this method, it only needs a
simple calculation to determine the smallest quantity (down to 0.1 c.c.)
of the sample that contains at least one of the microbes of indication.
For instance, if growth occurs in all the tubes from 4 to 10, and that
growth is subsequently proved to be due to the multiplication of B.
coli, then it follows that at least one colon bacillus is present in
every 10 c.c. of the water sample, but not in every 5 c.c. If, on the
other hand, the presence of the B. coli can only be proved in flask No.
7, then the average number of colon bacilli present in the sample is at
least one in every 50 c.c. (i. e., twenty per litre), but not one in
every 25 c.c. and so on.

The general outline of the method of identifying the members of the
coli-typhoid group is given in the form of an analytical schema--whilst
the full differential details are set out in tabular form.

ANALYTICAL SCHEME FOR ISOLATION OF MEMBERS OF THE COLI AND TYPHOID
GROUPS.

Nutrose agar.
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Red colonies. Blue colonies.
Escherich group. Gaertner and Eberth groups.
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Lactose peptone solution.
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Gas. No gas.
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