METHODS OF EXAMINING MILK 277 



ing 1 gramme of fuchsin in 10 c.c. of alcohol and 100 c.c. 

 of a 5 per cent, solution of phenol in water, and then 

 filtering the solution. The acid alcohol is prepared by 

 mixing 5 c.c. of nitric or one of the other mineral acids 

 with 95 c.c. of alcohol. After the smear on the slide has 

 been fixed, it is flooded with carbol fuchsin and the slide 

 is held over a Bunsen flame and the stain kept steaming 

 for 3 minutes. The slide is then rinsed with water and 

 the preparation treated with the acid alcohol until the 

 red color disappears. Next, the acid alcohol is rinsed off 

 with water and the preparation is stained for 3 minutes 

 with methylene blue, after which the slide is washed with 

 water, dried, and examined with the 1/12 oil immersion 

 objective. Any tubercle bacilli present will be stained 

 red; other organisms will be stained blue. While the 

 presence of tubercle bacilli may be accepted as proof that 

 the cow from which the milk came is infected with tuber- 

 culosis, failure to find these organisms cannot be re- 

 garded as positive evidence that the animal is not tuber- 

 culous. Tubercle bacilli may be present in small numbers 

 and escape detection on microscopic examination. The 

 so-called acid-fast organisms are also stained red by car- 

 bol fuchsin. They may be present in milk and butter, but, 

 apparently, they usually enter the milk after it is drawn 

 from the udder. Jensen is of the opinion that if precau- 

 tions are taken to prevent contamination of the milk 

 sample when it is drawn from the udder, these organisms 

 will very rarely cause errors in diagnosis. 



Antif or min Method. Take 5 c.c. of the milk to be ex- 

 amined and mix it with 5 c.c. of absolute alcohol, 5 c.c. 

 of ether, 10 c.c. of a 25 per cent, solution of antiformin 

 and 25 c.c. of normal saline solution. Place in an incu- 



