498 



WILLIAM A. LOCY AND OLOF LARSELL 



Thus are established the bronchial circuits which serve to make 

 a network of communicating air-passages throughout the lungs. 



Bronchial circuits of the adult lung. After the fifteenth day the 

 anastomosis of parabronchi goes on rapidly and results in a rich 

 profusion of intercomnuinicating air passages, imparting to the 

 lung tissue a structure that may be designated sponge-like. 



-Ent. 2 



> Par. 



42 



43 



Cran. 



Fig. 42 Portion of the mesial facet of the lung of an embryo of the fifteenth 

 day showing early stages of the anastomosis of parabronchi. X 73, reduced 3. 



Fig. 43 Similar view of the lung surface of an eml)ryo of the eighteenth day. 

 X 43, reduced i 



The passage ways are intricate and numerous and only the 

 chief sources of the parabronchial network of different lung 

 regions will be indicated. In observing the main features of the 

 distribution of branches of the bronchial circuits we have de- 

 pended chiefly on Wood's metal casts. Campana's detailed ac- 

 count of bronchial connections is impressive, but owing to the 



