FIGURE 107 



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

 embryo (series 107, slide IX, section 40), X 225. 



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. 

 9 Trachea. 

 10 Pulmonarv arterv. 



