HOW TO CANDLE EGGS. 



13 



can be used as a working guide in the candling of eggs. The terms 

 used to express the specific condition of the eggs are defined in the 

 general description of shell, white, and yolk, as discussed on pages 

 6 to 12. 



FRESH EGG. 1 



(Plates I and II.) 



BEFORE THE CANDLE. 



Air space: Not enlarged ; less than 

 three-fourths inch in diameter. 



White: Firm and clear. 



Yolk: Dimly seen through the white 

 as a shadowy object indistinct in 

 outline. The chick spot is not 

 visible. 



Distinguishing characteristics: No 

 shrinkage and general firm condi- 

 tions of white and yolk. 



Edible. 



OUT OF THE SHELL. 



White: Firm and thick ; opalescent ; 



reflects the light. 

 Yolk: Spherical and firm ; chick spot 



small with no sign of hatching. 



Color is uniform for the entire yolk, 



but varies in color from light yellow 



to deep orange, and is occasionally 



olive green. 

 Distinguishing characteristics: 



General firm condition of white and 



yolk. White, opalescent. 



HATCH-SPOT EGG. 



(Plate III.) 



BEFORE THE CANDLE. 



Air space: Usually enlarged. 



White: Thin and clear. 



Yolk: A distinct reddish glow around 

 the germinal spot, which is visible ; 

 usually located above the middle of 

 the egg. 



Distinguishing characteristic: Red- 

 dish glow on the yolk. 



OUT OF THE SHELL. 



White: Thin and clear ; no opales- 

 cence ; does not reflect the light as 

 strongly as does a fresh egg. 



Yolk: Bears a hatch spot; is flattened, 

 being especially weak around the 

 embryo. 



Distinguishing characteristic: 

 Hatch spot on the yolk. 



Edible. 



Occurrence: Chiefly during warm weather or hatching season. 



STALE EGG. 2 



BEFORE THE CANDLE. 



Air space: Enlarged ; the lower wall 

 may be movable in outline. 



White: Thin and clear. 



Yolk: Definite in outline ; sometimes 

 weak, and may occasionally have 

 dark, mottled areas. 



Distinguishing characteristics : En- 

 larged air cell and increased contrast 

 between white and yolk as compared 

 with a fresh egg. 



OUT OF THE SHELL. 



White: Thin; no opalescence; does not 



reflect the light as much as does a 



fresh egg. 

 Yolk: Flattened, and occasionally may 



have light, mottled areas. 

 Distinguishing characteristics: 



Thin white and flattened yolk. 



Edible. 



Occurrence: 



Among eggs not marketed promptly. 



x The color of a white egg before the candle is yellow with a pinkish tinge, that of a 

 brown egg is pinker, and that of a dark brown egg is almost red. In each instance the 

 color deepens in the region of the yolk. 



3 Illustrated in color in U. S. Dept. Agr. Bui. 51, PI. III. 



