FIGURE 111 



111 Transverse section through ventral part of upper thoracic region in a 

 13.5 mm. cat embryo (series 189, slide VIII, section 36), X 225. 



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. 



10 Pulmonary artery. ' . 

 22 Vagus. 



