6 BULLETIN 202, U. S. DEPARTMENT OF AGRICULTURE. 
ally of "old" milk — that is, milk from a cow in the last of its lac- 
tation period. 
The causes for a positive alcohol test may be summarized by the 
opinion of Ernst (8) who states that a positive alcohol test of fresh 
milk from a single cow indicates a physiological or severe patho- 
logical condition of irritation of the milk glands. There is, how- 
ever, a difference in the opinions of various investigators as to the 
reaction of the alcohol test to pathological conditions of the udder. 
Ruhm (28) noticed the alcohol test in milk from cows with in- 
fected udders. In some cases he found the test was positive during 
the infection and frequently a positive test was observed for three 
or four weeks later when the milk had a normal appearance and 
taste. He points out that in udder infection the milk may vary in 
many ways, and in consequence the alcohol test varies. Auzinger 
found that there was no relation between streptococci in infected 
udders and the alcohol test and that a positive test is produced 
through chemical changes in the secretions. Rullmann and Tromms- 
dorff (29) also observed a positive alcohol reaction in milk from cows 
with infected udders, but according to these authors the alcohol test 
shows no definite relation to the leucocyte count. They point out 
that the variation in ash salts and high albumin content probably 
influences the alcohol test. Campbell (5) also believes that the alcohol 
test is of value in determining the diseased condition of the udder. 
Besides udder infection Auzinger (2) states that the general infections 
and infections of the vaginal canal may cause a positive alcohol test; 
also that milk from cows which have aborted may coagulate with 
alcohol. Metzger (17), however, after a study of the alcohol test 
with milk from sick cows concludes that the milk from them shows 
no relation between the acidity and alcohol test. According to this 
author fever had no influence on the acid and alcohol tests. There 
was no relation between tuberculosis of the animal and the alcohol 
test. When animals were very lean from disease the milk inclined 
toward coagulation with alcohol. Infectious inflammation of the 
vagina was without influence on the test. Infection of the uterus 
shows almost regularly with the alcohol test, but not without ex- 
ception. Metzger also found that there was no relation between the 
alcohol test and various forms of indigestion. He points out that 
the chief value of the test lies in its use for the freshness of milk. 
We have not had an opportunity to study the alcohol test in its 
relation to the milk from sick cows, but from a study of the literature 
on this subject we are inclined to believe that the alcohol test would 
be of but little value as a routine test of the milk from a single cow 
or from a small herd. If the alcohol test were used regularly to test 
fresh milk of single cows a positive reaction would indicate some 
change in the milk from normal. Subsequent examination of the 
