FIGURES li»5 AXD 10(3 



105 Transverse section of ventral part of upper thoracic region in a 13 mm. cat 

 embryo (series 92, slide VII, section 30), X 225. 

 lOG Same, section 33. 



3 Ric:ht jirocaval vein. 



4 Atr(jphying embryonal vein, forming kernel in interior of developing 



and replacing lymphatic si)ace. 



5 Extraintimal or perivenous lymphatic space surrounding degenerating 



embryonal vein. 



7 Aorta. 



8 Oesophagus. 



9 Trachea. 

 22 ^'agus. 



