FIGURES 136 AND 137 



136 Same, section 20. 



137 Same, section 21. 



3 Right precaval vein. 



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. 



6 Precardinal or precava of left side. 



7 Aorta. 



9 Trachea. 

 10 Pulmonary artery. 

 22 Vagus. 



