106 BACTERIOLOGICAL ANALYSIS LESSON 



II. QUALITATIVE EXAMINATION. 

 Five samples of milk are supplied. 



Sample A contains Typhoid bacilli. 



B Bacterium coli commune. 

 C Streptococcus pyogenes. 

 D Bacillus diphtheriae. 

 E Tubercle bacilli. 



(a) Samples A 'and B : Bacillus of typhoid fever and the 

 Bacterium coli commune. 



Examine for typhoid bacilli and the Bacterium coli 

 commune, by preparing plates, in the manner described on 

 p. 105, using, however, carbol gelatine instead of ordinary 

 gelatine. These plates must be worked up as detailed on 

 p. 99. The nitration method is unfortunately not applicable 

 to milk. 



(b) Samples C and D: Streptococcus pyogenes and the 

 Bacillus diphtherice. 



(1) Use three sloped agar-agar tubes. 



(2) Stir up the milk, so as to distribute the suspended 

 organisms uniformly. 



(3) Dip a stout platinum loop into the milk. 



(4) Now make three parallel streaks on the surface of 

 the first agar-agar tube. 



(5) Without dipping the needle again into the milk, 

 make three parallel streaks on the surface of the second 

 agar-agar tube, and also of the third. 



(6) Place the three agar-agar tubes in the warm 

 incubator. 



