FIGURES 120 AND 121 



120 Same, section 7. 



121 Same, section 10. 



4 Atrophying embryonal vein, forming kernel in interior of developing 



and replacing lymphatic space. 



5 Extraintimal or perivenous lymphatic space surrounding degenerat- 



ing embryonal vein. 



7 Aorta 



9 Trachea. 

 10 Pulmonary artery. 

 22 Vagus. 

 32 Ventral mediastinal venous plexus. 



