476 



WILLIAM A. LOCY AND OLOF LARSELL 



Tra. - - - 



A 24 B 



R.Lg.-- 



Fig. 24 Side and ventral view of the central lung tube of an air injected 

 specimen of the 96-hour stage. Shows an early stage in the development of the 

 trachea. 



Fig. 25 Ventro-lateral view of the air injected lungs of an embryo incubated 

 100 hours. The trachea is definitely formed. 



Fig. 26 Cedar oil transparency of the lungs of a specimen incubated 4 days 

 20 hours, showing the exi)anded embryonic "vestibulum" and the occluded por- 

 tion of fhc bronchus. 



