STUDIES OF MARKET MILK. 189 
As would be expected the number of bacteria found in the 
milk of the different producers varies considerably from day 
to day as a result of variation in the conditions of cleanliness 
in obtaining and handling the milk for any given day. A 
study of Tables 27 to 37, however, shows that the increase in 
the average for each man is caused by a fairly constant increase 
in the numbers in the several experiments. In other words, 
those men whose milk shows the higher average for the entire 
series also shows the higher number in the majority of the 
daily tests. While this is true in general there are a few ex- 
ceptions. For example, in Table 29 the number of bacteria 
normally found in the milk is no greater than the numbers 
found in Table 27, the greater average in this case being due 
to the extremely high germ content of the milk on November 
11. In most cases, however, the average represents the nor- 
mal condition of the milk of each producer. 
Acid Producing Bacteria.—A study of the acid organisms in 
this group of tables shows that there is perhaps, even a greater 
variation in the numbers of acid bacteria from day to day than 
there is in the total numbers of bacteria. The number of acid 
bacteria found in any sample of milk seems to bear no direct 
relation to the total number of bacteria which the milk con- 
tained. ‘This is shown both in the daily tests for the different 
producers and also in the average of the acid bacteria for the 
entire series of samples from each man. Not only do the ac- 
tual numbers of acid bacteria vary greatly from day to day but 
the percentages also vary between wide limits, not infrequently 
there being less than 1 per cent. of acid bacteria while the 
same man’s milk may on another day contain over go per cent. 
regardless of the total number of bacteria found in the milk. 
There seems to be no constant relation between the per cent. 
- of acid bacteria and the total number of organisms contained in 
the different samples. It has already been brought out ina 
previous publication by this Station that the keeping quality 
of milk is not wholly dependent either upon the total number 
of bacteria or the percentage of acid organisms which it con- 
tains. ‘The species of organisms is of greater importance than 
the actual number from the standpoint of its keeping qualities. 
The same condition is shown very strikingly in these tables 
