THE EMBinOLOGY OF THE BIRD S LUNG 



17 



So far as we are aware a similar history of the formation of 

 the interclavicular sac has not been given. It has been known 

 since the time of Sappey ('47) that the single interclavicular sac 

 of the adult was produced b}^ the union of two parts, but the 

 formation of two moieties on each side from independent sources 



Ect. 6 - 



O.Abd 



Fig. 52 Diagram of the lateral surface of the right lung of a fifteen day em- 

 bryo, to show the recurrent bronchi of the abdominal and of the posterior inter- 

 mediate air-sacs. The outlines of the recurrent bronchi (in black) so far as rep- 

 resented were traced with the aid of the camera lucida from an air injected 

 preparation. Dotted portions diagrammatic. O.abd., orifice of the abdominal 

 sac; O.P.Int., orifice of the posterior intermediate; .4/(., anastomosis of recur- 

 rent bronchi. Other reference letters as before. 



and the details of their union had not, we beheve, been antici- 

 pated. 



We turn now from the air-sacs to the recurrent bronchi, the 

 embryonic history of which has been outlined from their earliest 

 appearance to the time when they have established their union 

 with other branches of the bronchial circuits. 



THE AMERICAN JOURNAL OF ANATOMY, VOL. 20, NO. 1 



