FIGURES 105 AND 106 



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

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



106 Same, section 33. 



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 degenerating 



embryonal vein. 



7 Aorta. 



8 Oesophagus. 



9 Trachea. 

 22 Vagus. 



