and to them add 1.0 c.c. of the
milk sample and a similar quantity of the diluted milk from capsules I,
II, and III and IV respectively.

11. Pour plates from the wort gelatine; label, and incubate at 20 deg. C.

12. Inoculate the liquefied agar tubes as follows:

To tube No. 1 add 0.1 c.c. of the milk sample.
2 add 0.1 c.c. from capsule I.
3 add 0.1 c.c. from capsule II.
4 add 0.1 c.c. from capsule III.
5 add 1.0 c.c. from capsule IV. }
6 add 0.1 c.c. from capsule IV. }

13. Pour plates from the agar tubes; label, and incubate at 37 deg. C.

14. After twenty-four hours' incubation "inspect," and after forty-eight
hours' incubation, "count" the agar plates and estimate the number of
"organisms growing at 37 deg. C." present per cubic centimetre of the
sample of milk.

15. After three, four, or five days' incubation, "count" the gelatine
plates and estimate therefrom the number of "organisms growing at 20 deg.
C." present per cubic centimetre of the sample of milk.

16. After a similar interval "count" the wort gelatine plates and
estimate the number of moulds and yeasts present per cubic centimetre of
the sample of milk.

NOTE.--Many observers prefer to employ gelatine agar (see
page 193) for the quantitative examination. In this case
gelatine-agar plates should be poured from tubes containing
the quantities of material indicated in step 8, incubated at
28 deg. C. to 30 deg. C. and after five days the "total number
of organisms developing at 28 deg. C." recorded.

~Qualitative.~--The qualitative bacteriological examination of milk is
chiefly directed to the detection of the presence of one or more of the
following pathogenic bacteria and when present to the estimation of
their numerical frequency.

Members of the Coli-typhoid group.
Vibrio cholerae.
Streptococcus pyogenes longus.
Micrococcus melitensis.
Staphylococcus pyogenes aureus.
Bacillus enteritidis sporogenes.
Bacillus diphtheriae.
Bacillus tuberculosis.

Some of these occur as accidental contaminations, either from the water
supply to the cow farm, or from the farm employees, whilst others are
derived directly from the cow.

In milk, as in water examinations, two methods are available, viz.:
Enrichment and Concentration--the former is used for the demonstration
of bacteria of intestinal origin, th