8 BULLETIN 565, U. S. DEPARTMENT OF AGRICULTURE. 



or in one which has been exposed to warm temperatures, as in summer 

 or by incubation. The condition of the white is indicated on candling 

 by the ease with which the yolk moves when the egg is rotated. For 

 example, in a fresh egg the white is so firm that the yolk sways 

 but little during candling, whereas in an egg with a weak white the 

 yolk moves much more rapidly. A further indication of a thin white 

 is seen on candling by the ease with which the white moves at the 

 air cell, which usually is enlarged. Out of the shell the difference 

 between a firm and a thin white is detected easily by pouring the egg 

 from one dish to another. As an egg becomes stale the amount of 

 thick white decreases and the amount of thin white increases. 



Out of the shell the white of the fresh egg has an opalescent 

 tinge, which characteristic is lost when an egg becomes stale. Eggs 

 are found sometimes in which the white is as thin as water. Such 

 eggs, however, are encountered rarely in ordinary candling. They 

 are detected by the exceedingly rapid motion of the yolk when 

 the egg is turned before the candle and by the very watery appear- 

 ance of the white at the air cell, which usually is broken. The watery 

 condition is caused, in most instances, by bacteria which penetrate 

 the shell when it is broken or wet and grow in the egg material, 

 destroying the mechanical structure of the white. TVlien such eggs 

 are opened the white flows out as readily as water and may be color- 

 less, although usually it is a yellowish brown. The odor is bad and 

 ammonia frequently is detected. Eggs with whites thus liquefied are 

 inedible. 



Several classes of bad eggs are indicated by discolored whites. Of 

 these, eggs with yellow, bloody, moldy, and green whites are the most 

 numerous. 



A yellow white represents one of the most common forms of egg 

 deterioration and is caused by the disintegration of the yolk. The 

 whites assume a clouded yellow color before the candle, the depth of 

 the color depending upon the amount of yolk present. (See PL VI.) 



Eggs with bloody whites are comparatively rare. They occur most 

 frequently among pullets' eggs in spring and fall and are caused by 

 rupture of blood vessels of the hen during the passage down the 

 oviduct of the egg before it is covered with the shell. The blood may 

 be present in the egg in the form of clots attached to the yolk or 

 distributed through the white. Such eggs are detected on candling 

 by the red color of the white and by the clots which appear as 

 irregular-shaped bodies floating in the egg. (See PI. X.) If eggs 

 with bloodj^ whites are inclosed in white shells, the red color is 

 detected easily by candling; if they are inclosed in brown shells, it 

 is not so easy to distinguish between the deep pink color caused by 

 the shell and the red color due to the presence of blood. An orange- 

 colored yolk also may make it difficult to detect an egg with a bloody 

 white. 



