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 



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B^CTER/A P£R CUB/C CENT/METER. 

 Fig. 1. — 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 counts 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). 





37, 859, 907 



510, 000, 000 



120, 000 



10, 388, 222 





114, 000, 000 





13, 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 



