CHAPTER XII 
EXAMINATION OF EGGS 
Eaaes have always been an important factor in the diet. As the 
density of population increased, especially in urban centers, the problem 
of securing fresh eggs became more and more acute. This was ren- 
dered more intricate by the fact that the greatest part of the annual lay 
is secured during the months of March, April, May and June. This 
makes it necessary to hold over, cither by cold storage or preservation, 
the abundance of these months against the want of the others. It has 
become of much importance to determine what factors are important 
in the keeping of this food product. 
A knowledge of the physiology of the hen which is concerned with the 
development of the egg is important in this connection. This has been 
well described by Benjamin (1915) from whose publication the following 
has been adapted. The oviduct of the hen is located in the rear part 
of the body cavity. The yolk is the first part to develop and this 
takes place in the ovary which may contain a large number of minute 
yolks. Each is contained in a sac, or follicle through which it secures 
its nourishment while developing. After development the yolk en- 
closed in its vitellin membrane escapes from the yolk sac and descends 
through the oviduct. If fertilization occurs, it takes place soon after 
the egg has entered the oviduct and before any albumen is deposited 
about it. About 40 per cent of the albumen is said to be laid down as 
the yolk passes through”the upper half of the oviduct. After passage 
through this albumen-forming region, it reaches the isthmus where the 
shell membranes are added with about 10 to 20 per cent more albumen. 
The uterus is then reached, where the remainder of the shell is added. 
During its passage through the vagina, just before its expulsion from 
the cloaca, it probably receives the outer gelatinous coating on the shell. 
The structure of the egg and shell is given in Figs. 75 and 76. 
The chemical composition of any food substance is important in 
determining the type of composition which may take place. This is 
especially true with a substance like eggs. The analysis quoted in 
Table XLVIITI is taken from the paper of Benjamin (1915). 
451 
