THE EMBRYOLOGY OF THE BIRD's LUNG 501 



It is now necessary to point out the distribution in the adult 

 lung of the ])ranehes of the six laterobronchi. The parabronchi 

 of the first laterobronchus occupy the ventral part of the lateral 

 face of the lung and anastomose with those of the transverse 

 branch of the fourth entobronchus. They also connect, both di- 

 rectly and indirectly, with recurrent bronchi from the anterior 

 intermediate air-sac. 



The second laterobronchus is the largest in the embryo and 

 also in the adult. It gives off branches between its origin and its 

 terminal bifurcations which send parabronchi to the caudo-ven- 

 tral part of the lung. The parabronchi of the second laterobron- 

 chus anastomose especially with those of the adjacent latero- 

 bronchi on each side of it, and with recurrent bronchi from the 

 two posterior air-sacs. 



The third laterobronchus, as described in its embryonic his- 

 tory, gives origin to the posterior intermediate air-sac. Like the 

 other laterobronchi, its parabronchi are distributed in the ventro- 

 lateral part of the lung, and they establish connections with the 

 network of air-pipes in this general region. 



The remaining laterobronchi are intermediate in size and im- 

 portance and may be included under one description. Their 

 branches serve the caudo-lateral i)art of the lung and form anas- 

 tomoses with the internal branches ol the recurrent bronchi from 

 the two posterior air-sacs, as well as with other air-pipes of this 

 part of the lung. 



In addition to the anastomoses specifically indicated above, 

 branches from all the laterobronchi form connections with 

 branches of the dorsobronchi, which ma}^ now claim our atten- 

 tion. 



Speaking, general, the branches of the dorsobronchi extend to- 

 wards the dorsal surface of the lung, and since this is relatively 

 near by, the dorsobronchi are short as compared with the latero- 

 bronchi. Before reaching the lung surface, they bifurcate and 

 the branches thus produced again divide one or more times. 

 The i^arabronchi from these sources are internal and unite with 

 those of neighboring laterobronchi, and, in the case of the more 

 posterior ones with recurrent bronchi. 



