FIGl'HE 12 



12 Transverse section of anterior thoracic region in a 14 mm. embryo (series 

 127, slide VHl, section 12), X 225. 



4 .Vtroijliying embryonal vein, forming kernel in interior of develop- 



ing and replacing lymphatic space. 



5 I'^xtraintimal or perivenous l\^llphatic space surrounding degen- 



erating embryonal vein. 

 () I'recanlinal or precava. resp. azygos of left side, 

 fj' Left a'?ygos A-ein, thoracic portion. 

 7 Aorta. 

 S Ocso|)liagu.-<. 



