446 BACTERIOLOGICAL ANALYSES 



11. Pour plates from the wort gelatine; label, and 

 incubate at 20 C. 



12. Inoculate the liquefied agar tubes as follows: 



To tube No. i add o . i c.c. of the milk sample. 



2 add o. i c.c. from capsule I. 



3 add o. i c.c. from capsule II. 



4 add o.i c.c. from capsule III. 



5 add i.o c.c. from capsule IV. ^ 



6 add o. i c.c. from capsule IV. J 



13. Pour plates from the agar tubes; label, and in- 

 cubate at 37 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 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 C." present 

 per cubic centimetre of the sample of milk. 



1 6. 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 C. to 30 C. 

 and after five days the "total number of organisms developing at 

 28 C." recorded. 



Qualitative. The qualitative bacteriological exam- 

 ination 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 f re quency . 



Members of the Coli-typhoid group. 



Vibrio cholerae. 



Streptococcus pyogenes longus. 



Micrococcus melitensis. 



