FIGURES 120 AND li'l 



120 Same, section 7. 



121 Same, section 10. 



4 .Vtropliying embryonal vein, forming kernel in interior of developing 



and replacing lympliatic space, 

 o Extraintimal or perivenous lympliatic space surrounding degenerat- 

 ing (>nd)ryon;d \'ein. 

 7 -Vorta 

 9 Trachea. 

 10 Pulmonary artery. 

 22 Vagus. 

 32 Ventr.il mediastinal venous plexus. 



