KKSIM RATION 



they soon become too small to be traced in this way. Micro- 

 scopical examination shows that each minute bronchial tube 

 finally divides into a cluster of short, blind, somewhat dilated 

 branches. These dilated terminations of each bronchial tube 



FIG. 53. Diagrams to show the structure of the lungs. 



A. a, an ultimate bronchial tulic opening into two infundibula, each consisting of .. 



number of alveolar chambers, />. 

 I'.. The wall of an alveolar chamlwr. a, the epithelium ; /-, partition between two 



alveoli, in which the capillaries lie ; c, fibres of elastic tissiir. 

 C. The blood-vessels of two alveoli, a, networks of capillaries ; f>, small arteries and 



vein-,. 

 1 . The same very highly magnified. 



are called infundibula. The wall of each infundibulum is 

 folded inwards, partly dividing the dilated cavity into a number 

 of rhainl>ers. Each of these chambers is called an alveolus. 



