CHAPTER VIII 



MUSCLES AND NERVES 



Muscles 



IRDS exhibit probably a greater degree of activity 

 than any other class of animals. Some seem 

 never to be still, and, whether soaring, fluttering, 

 running, hopping, climbing, dancing, or swimming, every 

 motion is the result of the action of one or more muscles. 



The entire flesh of a bird is divided up into layers 

 or bundles of distinct muscles, each having its function, — 

 raising, lowering, or in some way moving feathers, e3'e- 

 lids, legs, wings, tail, and other portions of the body. The 

 number and intricacy of these muscles can be imagined 

 when it is stated that in a goose there are more than twelve 

 thousand muscles or parts of muscles immediately be- 

 neath the skin, which serve to raise or otherwise move 

 the feathers. 



In a penguin the muscles immediately beneath the 

 skin are unusually well developed, and for an excellent 

 reason. By means of them the water "may be readily 

 expelled from the interstices of the plumage so soon as 

 the bird quits the water. Were it otherwise, in the low 

 temperature of the Antarctic region, which the majority 

 of these birds inhabit, their plumage would soon be frozen 



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