FACTORS INFLUENCING BACTERIAL CONTENT 377 
could be explained by a more careful investigation with regard to the 
condition of the animal. 
Barn Conditions. Some difference of opinion still exists with regard 
to the effect of barn conditions on the bacteria in milk. Harding et al. 
(1913) found that many procedures about the barn which were sup- 
posed to limit the number of bacteria contributed to milk might, under 
some conditions, increase the count. Ruehle and Kulp (1915) have 
shown that dusty air in a stable might increase the bacteria in milk 
but the increase, as such, would be of little sanitary importance. If 
these added bacteria developed, the increased count, at a later time, 
would come within sanitary considerations. Savage (1909-10) found a 
general agreement between the cleanliness of cows’ stables and the 
number of bacteria in milk. This also was borne out by the work of 
Brainerd (1911). 
Utensils. Recent work points to the conclusions that utensils 
may be one of the most important factors determining the number of 
bacteria in milk. Pease (1916) claims that, where high counts have 
been obtained in a dairy which has operated for a long time, they are due 
to inefticiently cleaned apparatus and by incubation of the bacteria on 
the moist surfaces of ihe cans, pails, etc. Prucha, Harding and Weeter 
(1915) reported some interesting data to substantiate this contention 
of Pease. With sterile utensils and sterile bottles, milk leaving the 
barn was found to contain 2588 bacteria per cubic centimeter and the 
bottled milk 3875. Where the utensils were simply washed and with 
only the bottles sterile, there were increases due to the pails of 57,077, 
up to the clarifier of 15,353, due to the clarifier of 172,763, due to cooler 
of 19,841 and due to the bottler of 247,611. More data on the same 
subject have been since reported by Prucha, Weeter and Chambers 
(1918). Ayers, Cook and Clemmer (1918) in a careful study of the 
factors involved in the production of a milk of low bacterial content, 
state as follows: ‘‘ Three simple factors were necessary for the pro- 
duction of milk with a low bacterial content, namely, sterilized utensils, 
clean cows with clean udders and teats, and the small top pail.” A 
fourth factor, holding the milk at a temperature near 10° C. or lower is 
necessary in order to keep the bacterial count low. Even cow manure 
was found to be of less importance in influencing the bacterial count 
than utensils. 
Age. The bacterial count is supposed among other things to yield 
information with regard to the age of the milk. Up to certain limits 
this is true, but soon a limit is reached beyond which no further growth 
may take place unless something happens to disturb the conditions. 
