FIGURES 142 AND lio 



142 Transverse section through ventral ])art of upjx'r Ihoracic region in a 15 

 mm. cat embrj^o (series 216, slide X, section 32), X 225. 



143 Same, section 33. 



3 Right precaval vein. 



4 Atroijhj'ing embryonal vein, forming kernel in interior of (hnclojiing 



and replacing lymphatic sjiace. 



5 Extraintimal or perivenous lymphatic sjiace surrounding degen- 



erating embryonal vein. 



7 Aorta. 



8 Oesophagus. 



9 Trachea. 



10 I'uhiionary artery. 

 22 Vagus. 



