ACCURACY IN COMMEECIAL GRADING OF OPENED EGGS. 11 
RELATION BETWEEN THE NUMBER OF BACTERIA AND THE PHYSICAL 
CONDITION OF THE EGG CONTENTS. 
CONDITION OF YOLK. 
The physical condition of an egg indicates to a large extent its 
state of preservation. The white of a strictly fresh egg is stiff and 
the yolk stands up firmly, as can be seen very clearly from Plate I. 1 
As the egg ages, the white becomes thinner, the yolk flatter, and 
the vitelline membrane weaker. When a stale egg is opened, the 
vitelline membrane frequently is ruptured and the contents of 
the yolk flows into and through the white, as illustrated in Plate 
III. 2 This type of egg is commonly called a "weak egg" or a "soft 
egg/ 1 and occurs most frequently in summer weather. Fertile eggs 
showing advanced hatch spots almost invariably contain weak yolks. 
Eggs produced in the spring of the year generally have a firm 
consistency; that is, both white and yolk have the viscosity of the 
fresh egg. Occasionally it happens that a portion of the contents of 
the yolk has seeped through the vitelline membrane into the white 
in sufficient amount to give it a yellowish tinge. (See Plate II.) 
Although this condition prevails before the egg is opened, it is rarely 
detected by candling. 
Because of their physical condition neither "soft eggs" nor eggs 
with incipient seeping yolks can be separated satisfactorily into white 
and yolk. These eggs appear to have whole yolks before the candle. 
If, on breaking, their odor is normal and the white not green, they 
may be considered suitable for baking and cooking. When the seep- 
age of the yolk is so advanced that it extends entirely through the 
white, the egg should be discarded. Such an egg has the appearance 
of a mixed rot before the candle. 3 
Further deterioration in the shell of a "weak egg" or "soft egg" 
results in the final rupture of the vitelline membrane and a partial 
mixing of white and yolk. This egg, which is one type of a mixed 
rot, is illustrated in Plate IV. The physical mixing of the white and 
yolk progresses until the egg becomes what is known as an addled 
egg or a white rot. Frequently, eggs containing blood rings or adher- 
ent yolks pass through the different stages of deterioration mi til 
they become addled eggs. 
It was found that the percentage of eggs with bacteria increased 
with the physical breaking down of the yolk, as shown by Table V. 
The percentage of eggs containing bacteria was as follows: 10.6 for 
eggs with whole yolks, 22.7 for soft eggs, and 43.5 for eggs with 
partially addled contents or with yolks adherent to the shell. 
The results of the examination of eggs with partially or entirely 
i Reprint from U. S. Dept. Agr. Bui. 51, pi. I, and U. S. Dept. Agr. Bui. 224, pi. XVII. 
2 Reprint from U. S. Dept. Agr. Bui. 224, pi. XIV. 
3 U. S. Dept. Agr. Bui. 224, pi. XVI. 
