CHAPTER XI. 
SOME ACCESSORIES. 
DIGESTION——CIRCULATION, BREATHING, TEMPERATURE—REPAIR 
OF THE MACHINE—CALL-NOTES AND SONG. 
No one who undertook to describe a steam-engine 
would ever dream of omitting all mention of the 
furnace. To do so would be to leave out, if not the 
part of Hamlet, yet a most important part. I have, 
therefore, determined to write a short chapter on 
certain “‘ accessories,” which would, perhaps, be 
more correctly called preliminaries. These pre- 
liminaries are matters of physiology, such as feeding, 
digestion, breathing, regulation of temperature. 
Digestion. 
A bird is a glorified reptile, and one great difference 
between him and his cold-blooded ancestors and his 
cold-blooded surviving relatives also is that he needs 
far more fuel to keep the flame of his life burning 
with its normal brightness than they require to 
maintain their slowly smouldering fires. The bird 
has a huge appetite, and, except when a demand 
for a prolonged, uninterrupted effort is made, he 
craves for ample meals at no long intervals. The 
boa-constrictor will go a week, or, in captivity, three 
weeks or more without eating, even during hot 
weather. But such abstinence does not suit a bird. 
