6 
BULLETIN" 303, U. S. DEPARTMENT OF AGRICULTURE. 
per cubic centimeter, while 41.75 per cent of the winter samples con- 
tained fewer than 1,000,000 per cubic centimeter. Finally, there 
remain 80.86 per cent of the summer samples and only 58.25 per 
cent of the winter samples which contained more than 1,000,000 
bacteria per cubic centimeter. These results are shown perhaps 
Fig. 1. 
B^CTER/A PER CU3/C CENT/METER. 
-Frequency curve showing bacterial content of summer and winter samples of ice cream. 
more strikingly in figure 1, where the samples have been plotted in a 
frequency curve, showing the difference in bacterial content between 
the summer and winter samples. 
The differences in the average cdunts of ice cream from different 
manufacturers at different seasons are summarized in Table 4. 
Table 4. — Summary of the bacterial counts of ice cream. 
Item. 
Summer 
series (94 
samples). 
Winter 
series (91 
samples). 
Average number of bacteria per cubic centimeter 
37.859,907 10,3S8,222 
510,000,000 1 114,000,000 
120,000 
These figures show a wide range in the bacterial content of ice 
cream during both the summer and winter months. The minimum 
counts of 120,000 during the summer and 13,000 in the winter series 
