76 Report OF DEPARTMENT OF BACTERIOLOGY OF THE 
It will be seen from the table that when the salt solution 
was used the germ content of the milk, while fluctuating con- 
siderably, had an average germ content of approximately 17,000 
per cc., omitting from the average the single very high number 
found on March 9. : 
. After the rubber parts had been.24 days out of the brine 
and had time to become a fair illustration of tubes handled 
in this way the series of examinations, April 14-24, gave an 
average of 188,380 per cc. This was approximately ten times 
the germ content found with the same machine when the salt 
solution was used. 
As the very nature of the influence which was being measured 
prevented a close comparison of the tubes kept in and out 
of the brine it was the intention to test the effect of the ma- 
chine shortly after the teat cups 1and rubber parts had been 
again placed in the salt solution. Unfortunately, in connection 
with this change, the cotton filters, to be later described, were 
also inserted in the machine. In 20 tests of the milk which 
were made between April 27 and May 1 the average germ 
content was 2600 per ce. While filters were responsible for 
a portion of this reduction the major part of it was undoubt- 
edly due to the action of the salt solution. The relative im- 
portance of these two factors, cotton filters and salt solution, 
is brought out in Table V. (See page 80.) 
Importance of care in placing tubes in brine.— It will be 
noted in the results of our studies with a brine solution that, 
occasionally, extremely high counts were obtained in indi- 
vidual cases. This was so pronounced in the case of some of 
our preliminary work that the cause was sought in the presence 
of air in the rubber tubes while in the brine. 
As a matter of convenience and to obviate the necessity of 
assembling the parts after taking them from the brine the 
teat cups and the accompanying rubber parts were left con- 
nected when placed in the salt solution. Unless care was ex- 
ercised in the act of immersing them air was inclosed in the 
tubes and the brine did not have free access to all parts of 
