ACCURACY IN" COMMERCIAL GRADING OF OPENED EGGS. 3 
those used in the cooperating egg-breaking plants for holding the 
eggs during grading. The cups were kept covered to prevent con- 
tamination from the air. 
In order that the grading might be uniform throughout the investi- 
gation and parallel the method followed in the cooperating egg- 
breaking plants, all of it was done by the same person, who was familiar 
with commercial procedures. Each egg was graded as good or bad, 
according to appearance and odor, and in case of doubt was graded 
also according to taste. 
After each egg was graded, a portion was removed to be examined 
for the number of bacteria and for the presence or absence of mem- 
bers of the B. coli group. 1 All of the eggs graded as good were then 
mixed to form a composite sample, which was examined for the total 
number of bacteria, the number of organisms producing gas in lactose 
bile, the percentage of moisture, and the amount of ammoniacal 
nitrogen as determined by the Folin titration method. 
After the egg had been thoroughly mixed, one cubic centimeter 
was withdrawn. 2 With this portion dilutions of 1 to 10, 1 to 100, 
and 1 to 1,.000 were made with physiological salt solution. From 
the three dilutions plates were made with nutrient agar as the 
medium. One cc of the first dilution was transferred to a fermenta- 
tion tube containing lactose bile. The plates were incubated at 
room temperature for 5 days and the fermentation tubes at 37° C. 
for 2 days. This procedure was followed in the examination of the 
individual egg. The composite samples were examined according 
to the methods described in Department Bulletin 51 (pp. 74 to 77). 
The number of bacteria in the individual eggs is expressed on the cubic- 
centimeter basis. As an egg which has been frozen for any length of 
time becomes so thick that it is not possible to deliver definite quan- 
tities accurately from a pipette, the portion of frozen egg to be exam- 
ined was weighed and the results expressed on the gram basis. The 
two bases are comparable because the specific gravity of the egg after 
the white and yolk are mixed is practically unity. 
EXTENT. 
During the course of the study 2,052 individual breaking-stock 
eggs, representing 29 samples, which varied in size from 66 to 72 eggs, 
were studied according to the plan just outlined. The samples were 
procured at fairly regular intervals between May 23 and October 27, 
1913, a period which covered the greater part of the egg-breaking 
season in the consuming center from which the eggs were chosen. 
1 The terms B. coli, B. coli group, and organisms or bacteria producing gas in lactose bile are used 
synonymously in this publication. 
2 For the purpose of this report, eggs which did not show the presence of bacteria in 1 cc have been 
considered sterile, since a smaller number of bacteria is negligible from the viewpoint of possible food 
contamination. 
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