DAIRY BACTERIA. 
267 
[Written specialty for the American Veterinary Review.] 
DAIRY BACTERIA. 
By A. S. Heath, M.D.V.S., Brooklyn, N. Y. 
Not only are there a larger number of bacteria in May and 
June, but they also differ in number in different cows. Professor 
Conn tested the milk of eight cows in one stable several 
times: In two of the cows the milk contained per loopful (a 
loopful is a drop about the size of the head of a large pin) 250 
bacteria per loop, while the milk from a third contained 20,000, 
and a fourth 60,000 in the same quantity of milk. There are no 
bacteria in the milk-glands, but there is some external favoring 
condition in the milk ducts and individuality of each cow to pro¬ 
duce bacteria. This being the case, it may be found that breed 
of cow may also exert a favoring influence in the production of 
bacteria, as the largest number of bovine bacteria in milk or 
cream gives the finest flavor and aroma to butter. The species 
of bacteria may be numerous. 
Prof. Conn found about 70 species of dairy bacteria. Milk, 
then, may be said to have a bacterial flora. But these are so minute 
as to make it extremely difficult to define bacterial species. But 
those producing acid, or souring of cream, gave the flavor and 
aroma of the butter, while those causing alkaline cream were 
those causing decay, and bad flavor. Acid bacteria produce no 
spores or seed, and a temperature of 158 F. destroys them, while 
alkaline bacteria do produce spores which are not destroyed at a 
temperature of 158 F., and continue decay. This is a serious 
argument against sterilized or pasteurized milk for human food. 
The inoculation of cream with acid and flavor and aroma- 
producing bacteria prevents the baneful effects of other species 
by doing their work quicker and better, thus shutting off the 
bad effects of alkaline or decay-producing bacteria. 
u Bacteriologists have for some time known that different 
species of bacteria may thus have a repressing influence upon 
each other. It has been determined , for instance , that the 
growth of the normal bacteria in milk prevents the growth there 
