der fluid = 0.1 oyster.
No. 5 with 1 c.c. cylinder fluid = 0.01 oyster.
No. 4 with 1 c.c. capsule I fluid = 0.001 oyster.
No. 3 with 1 c.c. capsule II fluid = 0.0001 oyster.
No. 2 with 1 c.c. capsule III fluid = 0.00001 oyster.
No. 1 with 1 c.c. capsule IV fluid = 0.000001 oyster.

16. Transfer 100 c.c. cylinder fluid (= 1 oyster) to an Erlenmeyer flask
and add 50 c.c. double strength bile salt broth, and label 7.

17. Duplicate all the above indicated cultures.

18. Put up the tube cultures in Buchner's tubes and incubate
anaerobically at 42 deg. C.

If growth occurs in tube 1 the organism finally isolated, e. g., B.
coli, must have been present to the extent of one million per oyster.

19. Complete the examination for members of the Coli-typhoid group and
sewage streptococci, as directed under Water Examination, page 429
(steps 11-21).

20. Inoculate a series of 6 tubes of litmus milk with quantities of the
material similar to those indicated in step 15; heat to 80 deg. C. for ten
minutes, and incubate under anaerobic conditions at 37 deg. C. Examine for
the presence of B. enteritidis sporogenes as directed under Water
Examination, page 438 (steps 7-10).

EXAMINATION OF SEWAGE AND SEWAGE EFFLUENTS.

Quantitative.--

_Collection of the Sample._--As only small quantities of material are
needed, the samples should be collected in a manner similar to that
described under water for quantitative examination and transmitted in
the ice apparatus used in packing those samples.

_Apparatus Required._--As for water (_vide_ page 420).

METHOD.--

1. Arrange four sterile capsules in a row and number them I, II, III,
IV.

2. Pipette 9 c.c. sterile bouillon into capsule No. I.

3. Pipette 9.9 c.c. sterile bouillon into capsules II, III, and IV.

4. Add 1 c.c. of the sewage to capsule No. I by means of a sterile
pipette, and mix thoroughly.

5. Take a fresh sterile pipette and transfer 0.1 c.c. of the mixture
from No. I to No. II and mix thoroughly.

6. In like manner transfer 0.1 c.c. from No. II to No. III, and then 0.1
c.c. from No. III to No. IV.

Now 1 c.c. of dilution No. I contains 0.1 c.c. of the original sewage.
1 c.c. of dilution No. II contains 0.001 c.c. of the original sewage.
1 c.c. of dilution No. III contains 0.00001 c.c. of the original sewage.
1 c.c. of dilution No. IV contains 0.0000001 c.c. of the original sewage