b.v. 





FIG. 300. 



ep c.t. s.s. 



al.s. al. 



FIG. 301. 



FIGS. 300 AND 301. SECTIONS OF THE LUNG DRAWN ON THE SAME SCALE OF MAGNIFICATION; FIG. 301 

 FROM A HUMAN EMBRYO OF FOUR MONTHS; FIG. 301, FROM AN ADULT. 



al., Alveolus; al. s., alveolar sac; br., bronchiole; b. v., blood vessel; c. t., outer layer of pleural connective 

 tissue; ep., pleural epithelium; lym., lymphatic vessel; pi., pleura; s. s., subserous connective tissue; 

 t. b.. terminal branch of the bronchiole. 



