8 BULLETIN 702, U. S. DEPARTMENT OF AGRICULTURE. 



mixed rot class, since all represent the first stages of yolk deteriora- 

 tion. The color before the candle of mixed and white rots, like that 

 of fresh eggs, depends on the color of both the shell and the yolk. 

 A light yellow yolk in a white shell has a pale yellow appearance 

 before the candle, and a brown shell or a dark yellow yolk in a wdiite 

 shell gives a reddish color. Brown shells or pale yolks in white shells 

 are factors which reduce the contrast between white and yolk. The 

 candler may very easily confuse the general yellow or pinkish color 

 of good eggs with that of a mixed or white rot if he does not study 

 the condition of the j^olk and allow for the color of the shell. Even 

 with close examination it may not be possible always to distinguish 

 between a whole and a broken yolk. In some instances the entire 

 yolk membrane may be so weak that the outline of the yolk changes 

 when the egg is turned, making it difficult to determine whether it is 

 whole or not. In other cases the presence of the yolk in the white, 

 due to seepage, can not be detected because of the opacity of the 

 shell. Again the white may be so firm that it tends to prevent the 

 spreading of the yolk material, even though the yolk sac may be rup- 

 tured. These different forms of yolk deterioration are readily rec- 

 ognized when the egg is opened. 



Table 2 shows that out of 187 cases of eggs 505 white rots and 

 450 mixed rots were found, of which 89.71 per cent and 67.12 per 

 cent, respectively, were detected by commercial candling. The pro- 

 portion of these eggs miscandled in refrigerator eggs was practically 

 the same (Table 2). As white rots are an advanced form of mixed 

 rots, and present more distinctive characteristics before the candle, it 

 is to be expected that the error in candling would be less. The data 

 given in Table 3 further confirm these findings. 



EGGS WITH SLIGHTLY STUCK YOLKS. 



The egg with the slightly stuck yolk, representing one of the 

 most common types of deterioration in summer, is very frequently 

 miscandled. A pale yolk or a brown shell increases the difficulty 

 of detection. In addition, when the yolk is stuck by a small area 

 onl}'^ it may sway back and forth so readily that it is difficult to 

 determine whether it is free or adherent. If the turning during the 

 candling tears the yolk from the shell it may be so slightly broken 

 and the white so firm that it is almost impossible to determine 

 whether the 3^olk is Avhole or broken. The yellow stain on the shell 

 marking the place where the yolk was stuck and which is charac- 

 teristic of this egg when out of the shall is not always visible before 

 the candle. 



Checking the decision made by candling with the appearance of 

 the egg out of the shell is one of the most effective means of becom- 



