METHODS OF EXAMINING MILK 277 
ing 1 gramme of fuchsin in 10 c.c. of alcohol and 100 e.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. 
Antiformin Method.—Take 5 c.c. of the milk to be ex- 
amined and mix it with 5 e.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- 
