FIGURES 108 AND 109 



108 Transverse section of ventral part of upper thoracic region in a 13.5 mm. 

 cat embryo (series 223, slide X, section 11), X 225. 



109 Same, section 12. 



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. 

 9 Trachea. 

 22 Vagus. 



