42 UNIVERSITY OF WISCONSIN STUDIES 
although the real germ content was vastly higher in the sour 
milk. It should be noted that this is a comparison of the 
results from individual plates and that the average from a 
considerable number of simultancous plate determinations 
gave more logical results. A study of the above data by Dr. 
Reitz showed that the results of approximately twenty-five 
simultaneous plate determinations should be averaged to give 
results which are satisfactorily accurate.** Ordinary labora- 
tory studies are made with four to six simultaneous plates*’ 
but routine municipal determinations are frequently based 
upon the count from single plates. In the face of the demon- 
strated variability of bacterial plate counts, the use of the 
results from single plates in municipal laboratories is ex- 
tremely unsatisfactory. 
Another stumbling block in the way of bacterial plate 
standards is the fact that there are so few municipalities 
equipped with men and facilities for making as accordant 
plate counts as those discussed above. The number of cities 
in the United States thus properly equipped is considerably 
iess than the number which have already adopted such muni- 
cipal standards. Any standard of keeping quality which 
is to be a satisfactory aid in measuring the keeping quality 
of city milk must be much more widely applicable than 
standard bacterial plate counts are at present. The ‘‘little 
plate’? method suggested by Frost?* meets some of these ob- 
jections but as yet has not been commonly employed. 
The direct microscopic estimation of the bacteria in milk 
has a number of advantages over the plate count among which 
are the quickness with which it can be made and the relatively 
*® Data presented by H. L. Reitz and H. A. Harding to the Laboratory 
Section of the \mer. Public Health Association at the Rochester meetins, 
1914, 
“TM. J, Prucha and H. M. Wecter, Bul. 199, Ill. Agr. Exp, Sta., p. 31, 
1917. 
*“W. D, Frost, Rapid Method of Counting Bactcria in Milk in Sei, 42, 
pp. 255-256, 1915; Comparison of a Ranid Method of Counting Bacteria in 
Milk with the Standard Plate Method in J. of Inf. Dis., 19, pp. 2738-287, 
1916; A Rapid Method of Counting Bacteria in Milk and Other Richly 
Seeded Materials in J. Amer. Med. Asso. 66, pp. 889-890, 1916; Counting 
the Living Bacteria in Milk—A Practical Test in J. of Bact., 2, pp. 567- 
583, 1917: Improved Technique for the Micro or Little Plate Method of 
Counting Bacteria in Milk in J. of Inf. Dis.. 28, pp. 176-184, 1921, 
