368 PUBLIC HEALTH BACTERIOLOGY 



Qualitative Examination. 



i. For Faecal Organisms. 



Inoculate tubes of MacConkey's bile-salt glucose peptone 

 (10 c.c.) with i c.c. from each dilution, beginning with the 

 weakest (i cc=o-oooooi c.c. milk, or one-millionth), and 

 continuing in reverse order. Also one tube with i c.c. of 

 undiluted milk, and one tube of double strength broth 

 (MacConkey's) with 10 c.c. of undiluted milk. Incubate 

 for two days at 37 C. All the cultures showing acid and 

 gas are subcultured as detailed under Water (page 353). 



2. For B. Enteritidis Sporogenes. 



Inoculate tubes containing 15 c.c. sterile whole milk, with 

 o-ooi c.c, o-oi c.c, o-i c.c, 1 c.c, 10 c.c and a tube con- 

 taining 30 c.c. with 100 c.c Heat to &a C. for 10 minutes 

 for the smaller amounts, and 20 minutes for the larger. 

 Incubate anaerobically at 37 C. for 2 days, and observe 

 for the " enteritidis change or reaction " (page 319). 



3. For Tubercle Bacilli. 



Centrifugalize and take sediment, make a film, fix, 

 clear with ether and alcohol, and stain for acid-fast 

 bacilli. Failure to find them is inconclusive ; on the 

 other hand, all acid-fast forms found are not tubercle 

 bacilli. In case of failure, or of success to prove nature, 

 use the animal experiment. Centrifuge 250 c.c. of milk, 

 add sterile water to sediment, and inject into a 1 guinea-pig 

 intraperitoneally. The animal is killed in three weeks (if 

 it has not died before that time from septicaemia or severe 

 infection), and the carcase sought for typical lesions. 

 Among acid-fast organisms, the forms found in hay, butter, 

 etc., are slightly pathogenic, but are easily distinguished by 

 their rapid growth on cultivation. An attempt at cultiva- 

 tion from the lesions in the guinea-pig should therefore be 

 made. 



The following excerpt from Dr. J. Hume Patterson's 

 Report for 1910, to the County M.O.H., Lanarkshire, 

 details some experiments on the distribution of the tubercle 

 bacilli in the " fore," " mid," and " strippings " milk : 



