THE EMBRYOLOGY OF THE BIKD's LUNG 



465 



Well injected specimens of this age show that the blood supply 

 predominates in the dorsal region of the lung. After the air- 

 sacs are well projected their walls are relatively thin and they 

 do not exhibit any blood vessels that will take the India ink in- 



Cerv.Sc, 



P.lntSc. 

 -Abd.Sc. 



B 



Fig. 16 (A) Dissection exposing the left lung of an etnbiyo of the ninth day 

 of incubation showing five air-sacs projecting from the lung. The mesial moiety 

 of the interclavicular is hidden from view. (B) Heart and right lung of the same 

 specimen. Modified from a sketch by 0. PI. A. Rech. 



