FIGURES 42 AND 43 



42 Same, section 26. 



43 Transverse section through left side of lower cervical region of a 13.5 mm. 

 cat embryo (series 189, slide VII, section 10), X 150. 



1 Sympathetic nerve. 



8 Oesophagus. 



9 Trachea. 



11 Jugular lymph sac. 



12 Jugular lymph sac, thoracic duct approach. 



16 Dorso-medial somatic venous tributaries. 



17 Prevertebral venous plexus. 



21 Thymus. 



22 Vagus. 



23 Left carotid artery. 



24 Thyrocervical artery. 



25 Internal jugular vein. 



46 Left superior intercostal vein. 



