RESPIRATION. J 255 



ft v v OF THE 



heart of a fish throws the blood only to the gills, and not to the rest of 

 the body as in other animals. This is the reason why the gills are red, 

 while the other parts of a fish are white. Respiration in fishes is, 

 therefore, performed by taking water into the mouth, and forcing it 

 through the gills ; in this manner the air contained in the water is 

 brought in contact with the thin coats of the blood-vessels, through 

 which the oxygen is absorbed. 



Questions. What is meant by respiration ? by inspiration ? by 

 expiration? How are the parts concerned in respiration arranged? 

 What bones are concerned ? Describe the position of the ribs. What 

 muscles are chiefly concerned in respiration ? Describe the intercos- 

 tals, the diaphragm. How does the diaphragm act in inspiration ? 

 In expiration ? What causes the deecant of the ribs in expiration ? 

 Describe the structure of the lungs. Whawcalled in the lower animals ? 

 What are the pleurae ? the mediastinTfinipHow many compartments 

 is the chest divided into ?) In which iVjthe heart ? What is the 

 trachea ? What does it end in ? How large are the air cells ? What 

 is the office of respiration ? What amount of surface do the air cells 

 present ? How does the blood get in contact with the air ? Describe 

 the process of respiration. How does tight lacing injure the health ? 

 What happens if a hole is made into the cavity of the chest ? What 

 is the weight of the atmosphere equal to ? Of what gases is it com- 

 posed ? What effect do vegetables have on air ? What is oxygen ? 

 azote ? What is the effect of respiration on air ? How much oxygen 

 is consumed by a man in twenty-four hours ? How do insects breathe? 

 the earth-worm ? fishes ? birds ? the whale ? &c. 



