96 Report of the Department of Bacteriology of the 



that the average of the plate counts in this group from Farm A is 

 higher, 63,000 bacteria per cubic centimeter, than from Farms 

 B, C and D, 22,000 per cubic centimeter. 



Table VIII shows a combined summary of all the counts from 

 Farms A, B, C and D. 



Because of the selection of counts in Table VIII the range between 

 the maximum and minimum counts according ta the plate method 

 is limited, while no idea is given as to the maximum and minimum 

 counts according to the microscopic method. Yet, in averaging 

 any series of figures, this point must be considered. For this reason, 

 the extent of the differences between the maximum and minimum 

 microscopic counts given in Table VIII are tabulated in Table IX. 



Table IX. — Minimum and Maximum Counts Included in the Averages in the 



Fourth Column of Table VIII. 

 Numbers computed for a cubic centimeter. 



COMBINED SUMMARY OF ALL SAMPLES STUDIED. 



The averages obtained from the less detailed examination of sam- 

 ples of milk from thirty-three additional farms are combined in 

 Table X with those from Farms A, B, C and D to show the com- 

 parative averages and the ratios between counts made by both 

 methods on all samples studied in this investigation. 



This summary of the results secured from the examination of 

 390 samples of milk shows practically the same ratios as those given 

 in Table VIII, except in one instance. Where the plate count is 

 between 10,000 and 100,000 the ratio given in Table X is noticeably 

 larger than the similar ratio in Table VIII. In this case the total 

 number of bacteria according to the microscopic count is about 

 twenty-five instead of sixteen times as great. As previously stated, 

 the microscopic counts included in this table, covering the work 

 done on the thirty-three farms, were made more rapidly than those 



