ACCURACY IN" COMMERCIAL GRADING OF OPENED EGGS. 
13 
POSITION OF YOLK. 
When viewed before the candle the yolk of a perfectly fresh egg 
is found to be located slightly above the meridian and is symmetrical 
with the long axis of the egg. It is indistinct in outline and moves 
very sluggishly as the egg is turned. As the egg ages the yolk appar- 
ently becomes more opaque and may settle against the lowest part 
of the shell. 
Of all the eggs studied 1,795, or 87.5 per cent, were eggs with free 
yolks; 248, or 12.1 per cent, eggs with yolks settled close to the shell, 
but not adhering; and 9, or 0.4 per cent, eggs in which the yolks 
were either addled or adherent to the shell. Fewer eggs with adher- 
ent yolks or addled contents are listed in Table VI, which gives the 
results of examination of eggs graded by the candling method, than 
are listed in Table V, where the eggs were graded out of the shell. 
The reason for this is that eggs with slightly adherent yolks are often 
difficult to detect by candling, especially if the shell is brown. 
These results confirm earlier studies * of similar eggs, in that they 
show that a settled yolk is not in itself an indication that the egg 
contains bacteria. 
Table VI. — Relation of bacteria in eggs to position of yolk. 
I. EGGS CONTAINING BACTERIA. 
Position of yolk. 
Num- 
ber 
ex- 
am- 
ined. 
Num- 
ber 
posi- 
tive. 
Per 
cent 
posi- 
tive. 
1,795 
248 
9 
241 
32 
5 
13.4 
Settled 
12.9 
55.5 
Total 
2,052 
278 
13.5 
II. VARIATION LN BACTERIAL CONTENT OF EGGS CONTAINING BACTERIA. 
Number of bacteria per cc. 
Position of yolk. 
101 to 1,000. 
1,001 to 
10,000. • 
10,001 to 
50,000. 
50,001 to 
100,000. 
100,001 to 
500,000. 
Over 
500,000. 
Total 
num- 
ber of 
Num- 
ber of 
eggs. 
Per 
cent. 
Num- 
ber of 
eggs. 
Per 
cent. 
Num- 
ber of 
eggs. 
Per 
cent. 
Num- 
ber of 
eggs. 
Per 
cent. 
Num- 
ber of 
eggs. 
Per 
cent. 
Num- 
ber of 
eggs. 
Per 
cent. 
eggs. 
Free moving 
Settled 
65 
10 
1 
27.0 
31.2 
20.0 
44 
18.3 
31 
5 
12.9 
15.6 
19 
1 
7.8 
3.1 
29 
3 
12.0 
9.4 
53 
13 
3 
22.0 
40.6 
60.0 
241 
32 
Addled or adherent.. 
1 
20.6 
5 
Total 
76 
45 
36 
20 
32 
69 
278 
U. S. Dept. Agr. Bui. 51, pp. 12, 30, 31. 
