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ZOOLOGY 



Adaptations in the bills of birds. 



The rate of respiration, of heart beat, and the body temperature 

 are all higher in the bird than in man. All these correlated facts 

 show that, because of the increased activity of the bird, there 

 comes a necessity for a greater and more rapid supply of oxygen, 

 an increased blood supply to carry the material to be used up in 

 the release of energy, and a means of rapid excretion of the wastes 

 resulting from the process of oxidation. The bird may be com- 

 pared to a high-pressure steam engine. In order to release the 

 energy which the bird uses in flight, a large quantity of fuel which 

 will oxidize quickly must be used. Birds are large eaters, and the 

 digestive tract is fitted to digest the food quickty and to release the 

 energy when needed, by having a large crop in which food may be 

 stored in a much softened condition. As soon as the food is part 

 of the blood it may be sent rapidly to the places where it is needed, 

 by means of the large four-chambered heart and large blood 

 vessels. 



This is one of the greatest adaptations to the active life led 

 by a bird. Man breathes from twelve to fourteen times per 

 minute. Birds breathe from twenty to sixty times a minute. 

 The lungs are not large, but the bronchial tubes are continued 



