New YorK AGRICULTURAL EXPERIMENT STATION. 95 
room for improvement in this particular, a 10 per ct. solution 
of common salt is fairly satisfactory for immersing the tubes. 
The limit to which the germ content of the milk can be re- 
duced turns largely upon the efficiency of the air filters and 
these have varied widely upon the different types of machines 
which have been studied. 
Owing to the constantly shifting type of machine it has not 
been practicable to study the effect of seasonal variation upon 
the germ content of the milk. Such a study also is rendered 
difficult by the fact that there are important factors influenc- 
ing the germ content of the machine-drawn milk which have 
not yet been determined. As a result, high numbers are occa- 
sionally obtained when there is no observed occasion for them. 
It will be necessary to get these factors fully under control 
before accurate work can be done in measuring the influence 
of the various factors. ; 
One of the greatest difficulties in connection with this work 
has been to insure a proper degree of care in manipulating the 
machines and this difficulty will follow any attempt to produce 
milk with a low germ content on a commercial scale. The 
machines have now reached a degree of perfection where they 
can be reasonably expected to deliver milk of a germ content 
comparable with good hand milking when given proper at- 
tention. 
