THE VITAL PROCESSES 



Larynx 



divisions, called lobules (Fig. 33)- Each lobule receives a 

 distinct division of an air tube and has in itself the struc- 

 ture of a miniature lung. 



3. In the lobule the air tube divides into a number of 

 smaller tubes, each ending in a thin-walled sac, called an 



infundibulum. The 

 interior of the in- 

 fundibulum is sepa- 

 rated into many small 

 spaces, known as the 

 alveoli, or air cells. 



The lungs are re- 

 markable for their 

 lightness and deli- 

 cacy of structure. 1 

 They consist chiefly 

 of the tissues that 

 form their sacs, air 

 tubes, and blood ves- 

 sels ; the membranes 

 that line their inner 

 and outer surfaces ; 



and the connective 

 FIG. 33. Lungs and air passages seen . 



from the front. The right lung shows the lobes tlSSUC that binds 

 and their divisions, the lobules. The tissue of these parts together, 

 the left lung has been dissected away to show J\\ these tissues are 

 the air tubes. i i 



more or less elas- 

 tic. The relation of the different parts of the lungs to 



1 The peculiar work devolving upon the organs of respiration necessitates a 

 special plan of construction one adapted to the properties of the atmosphere. 

 Being concerned in the movement of air, a gaseous substance, they will naturally 

 have a structure different from the organs of circulation which move a liquid 

 (the blood). All the organs of the body are adapted by their structure to the work 

 which they perform. 



