FIGURES 138 AND 139 



138 Same, section 22. 



139 Same, section 23. 



3 Right precaval vein. 



4 Atrophying embryonal vein, forming kernel in interior of developing 



and replacing lymphatic space. 



o Extraintimal or perivenous lymphatic space surrounding degen- 

 erating embryonal vein. 



6 Precardinal or precava of left side. 



7 Aorta. 



9 Trachea. 

 10 Pulmonary artery. 

 22 Vagus. 



