FIGURES 83 AND 84 



83 Transverse section of left lower cervical region in a 17 mm. cat embryo 

 (series 142, slide X, section 13). X 225. 



84 Same, section 16. 



1 Sj'mpathetic nerve. 



12 Jugular l>'niph sac, thoracic duct approach. 



13 Jugular lymph sac, jugular approach. 



14 Jugular lymph sac, subclavian approach. 



21 Thymus. 



22 Vagus. 



24 Thyrocervical artery. 



25 Internal jugular vein. 



29 Jugulo-subclavian trunk. 



