334 



DETAILED SYNTHESIS. 



FIG. 218. Fig. 218. 1, 



2, lungs, drawn 

 aside from the 

 hearts; 3, the 

 trachea; 4, 5, 

 the bronchii ; 



6, ventricle of 

 front,right,pul- 

 monary, or res- 

 piratory heart ; 



7, its auricle; 



8, left, back, or 

 systemic heart; 



9, 10, vena ca- 

 va, opening in- 

 to?; 11, aorta; 

 12, pulmonary 

 or respiratory 

 artery ; 13, 14, 



its branches; 15, a cord ; 16, upper edge of 8; 17, 18, 19, 20, pulmonary 

 or respiratory veins, opening into 16 or 8. 



parts together; and of an external covering (pleura 

 pulmonaiis). (See Fig. 96.) 



975. THE BRONCHII AEE CONSTRUCTED like the tra- 

 chea, only in the smaller branches, instead of one 

 C-shaped cartilage, several pieces complete the ring, in 

 which also there is more muscular tissue. The mucous 

 membrane also grows thinner as the air-cells are ap- 

 proached. 



976. AIR-CELLS are 

 an expansion of the lin- 

 ing of the minute bron- 

 chii, its fibrous portion 

 being diminished al- 

 most to nothing, and its 

 lining cells also being 

 modified. The sides of 

 the cells are saculated 

 for the purpose of presenting a greater extent of surface. 

 (See much magnified cells in adjoining Fig.) 



FIG. 219. 



Describe Fig. 218. 975. How are ? 976. What are ? Describe Fig. 219. 

 |3ee Fig. 94 ) 



