THE EMBRYOLOGY OF THE BIHD's LUNG 473 



2. THE DEVELOPMENT OF THE HROXCinAJ. TREE 



In this section will be described the intrapulnionary phenom- 

 ena of development of the bronchial tree. Although, morpho- 

 logically speaking, the air-sacs and r(>current l^ronchi are parts of 

 the bronchial tree they will be considered separately. 



f /■ 



Fig. 22 Dissection cxposinfi tiu' icil iuii^ t('riitoi\- of ;i chick embryo of thir- 

 teen davs incuhat ion. Modiflod from a skctcli l)v (!. H. A. Rech. 



As Campana pointed out, there is no 'bi-onchial tree' of the 

 adult bird's lung in the sense in which this designation is used for 

 mammals. No bronchial twigs of the adult avian lung termi- 

 nate blindly. On the contrary, there is established a network of 



