KESPIRATIOX. 135 



the blocd some of its carbonic acid and its water. By this 

 change the blood is relieved of its exhausted and dead parti- 

 cles, and receives new and life-giving particles in their stead. 

 The color is changed from a dark purple to a bright scarlet. 

 After this, the blood is ready again for the sustenance of life, 

 and is sent back, through the pulmonary veins, to the left 

 side of the heart, to be sent again, through the arteries, to 

 the whole of the body, carrying nutriment to support it, and 

 oxygen to combine with its dead carbon. 



297. Carbon and hydrogen compose the principal portion 

 of the wasted and exhausted particles of the living body, and 

 these are thrown into the veins. There they meet with the 

 oxygen that has been absorbed from the atmosphere in the 

 lungs, and carried in the blood, through the arteries, to the 

 capillaries and the minute veins. There these, the hydrogen 

 and the carbonic particles, and the oxygen, meeting together, 

 unite and form carbonic acid gas and water. These new 

 compounds are then sent, with the venous blood, through 

 the veins, to the heart, and thence to the lungs. 



CHAPTER V. 



Venous or purple Blood changed to arterial or scarlet Blood. 

 Color of venous Blood seen in Veins of Hand, and of arterial 

 Blood in flushed Cheek. Oxygen consumed in Respiration. 

 Carbonic Acid given out. Water given out through Lungs. 

 Other Matters. Foul Odors in Breath. Offensive Breath. 



298. THE blood enters the lungs a compound of three 

 kinds of matter the old blood, which had not been used for 

 the purpose of nutrition, the old wasted particles, which 

 are now seeking an outlet, and the new chyle from the 

 digestive organs. ( 264, p. 120.) All this heterogeneous 

 mass is unfit for the nutrition of the animal body. Its color 

 is purple. In this compound no free oxygen is present, but 

 carbonic acid and water are abundant. When the blood 



