452 BACTERIOLOGICAL ANALYSES 



numbers, in retail milk. Its detection, therefore, unless in enor- 

 mous numbers, (when it indicates want of cleanliness), is of little 

 value. 



2. Vibrio Choleras. Inoculate tubes of peptone 

 water by using the same amounts as in the search 

 for members of the Coli-typhoid groups (vide ante 1-3) ; 

 incubate aerobically at 37 C. and complete the exam- 

 ination as detailed under the corresponding section of 

 water examination (see page 43 9) . 



3. B. Enteritidis Sporogenes. Inoculate tubes of 

 litmus milk with similar amounts to those used in the 

 previous searches, omitting tube No. i (vide ante 1-3) 

 place in the differential steriliser at 80 C. for ten 

 minutes and then incubate anaerobically at 3 7 C. for 

 a maximum period of forty-eight hours. Complete 

 the investigation as detailed under the corresponding 

 section of water examination (see page 438). 



4. B. Diphtherias. 



(A) i. Plant three sets of serial cultivations, twelve 

 tubes in each set, from (a) cream C 2 , (b) deposit D 1 

 upon oblique inspissated blood-serum, and incubate 

 at 37 C. 



2. Pick off any suspicious colonies which may have 

 made their appearance twelve hours after incubation, 

 examine microscopically and subcultivate upon blood- 

 serum and place in the incubator; return the original 

 tubes to the incubator. 



3. Repeat this after eighteen hours' incubation. 



4. From the resulting growths make cover-slip 

 preparations and stain carbolic methylene-blue, Neis- 

 ser's method, Gram's method. Subcultivate such as 

 appear to be composed of diphtheria bacilli in glucose 

 peptone solution. Note those in which acid produc- 

 tion takes place. 



5. Inoculate guinea-pigs subcutaneously with one 

 or two cubic centimetres forty-eight-hour-old glucose 



