STUDIES OF MARKET MILK. ri yp 
The results given in this paper were obtained from samples 
taken from the milk of individual producers as it was delivered to 
the shipping station from which it was sent to Providence, R. I. 
METHOD OF THESE EXPERIMENTS. 
As already stated the milk used in these experiments was 
obtained from the individual producers as it was delivered to 
the shipping station each morning. This work was made pos- 
sible through the kindness and codperation of the Providence 
Dairy Co. at whose plant the samples were taken. As each 
man’s milk was received at the station his night’s and morn- 
ing’s milk was thoroughly mixed and a sample taken. At this 
time the temperature of the milk was taken and also the lac- 
tometer reading which was later used for computing the total 
solids. A small laboratory for bacteriological work was fitted 
up in the building and as soon as samples were obtained they 
were carried to this room where plate cultures were at once 
made. For this work the culture media used was the milk 
sugar litmus gelatin which we commonly use for our milk 
work where a differentiation of species is desired. ‘Three dif- 
ferent dilutions were used for each sample of milk, duplicate 
plates of each dilution being made. The results given, there- 
fore, represent the average from the six plates made. At the 
beginning of this work it was difficult to use dilutions which 
would give us the proper number of colonies per plate, but 
after each man’s milk had been plated a few times we were 
able to settle upon certain dilutions for his milk which gave 
quite satisfactory results in each case. It was found necessary 
to use different dilutions for the different men inasmuch as the 
germ content of the milk of the different producers varied 
so greatly. After plating the day’s samples the plates were 
brought to the Station laboratory for incubation. Samples of . 
the milk were also brought to the laboratory for determining 
the butter-fat and the keeping quality. The latter was deter- 
mined by keeping the samples under uniform conditions until 
they reached the laboratory when they were placed in a con- 
stant temperature of 20° C. and the time of curdling noted. 
From the samples brought to the laboratory notes were taken 
on the amount of insoluble dirt contained in the milk. Owing 
to the amount of work involved in making quantitative dirt 
