CHAPTER VIII 
THE BIRD WITHIN THE EGG 
IN writing of birds, as of other subjects, it is logical 
to begin ab ovo. ‘This system, however methodical 
and German it may-be, I have deliberately avoided, 
since in practice it is unwise to begin with what is 
least intelligible. Now that the reader understands 
the circulation of the blood, he will more easily under- 
stand some important points in the development of 
the embryo. If the pages that describe the circula- 
tion are not fresh in his memory, he is recommended 
to look them up before reading this chapter. 
If a sitting hen be watched upon her nest, she 
may sometimes be seen to raise herself a little, and 
stir the eggs with her feet. Many people have 
imagined that the sole object was to turn them 
over. This may be an advantage, since the eggs 
require damping, and, by this means, each side in 
turn is moistened by the ground. No turning is 
required to ensure that the embryo which lies just 
1 Eggs that are much exposed to damp in the nest have a 
waterproof layer. 
Tt 2 
