PLATE 3 



EXPLANATION OF FIGURES 



IS Human embryo, 10.1 mm. in length, 623 — 10-2 — 4X240. Transverse sec- 

 tion through oesophagus showing vagus trunks and oesophageal plexus, oep, 

 cell aggregates in oesophageal plexus; v, vagus trunks. 



19 Human embryo, 10.1 mm. in length, 623—13—2—2—2X240. Transverse 

 section through oesophagus just above upper level of heart showing oesophageal 

 plexus, oep, cell aggregates in oesophageal plexus; vb, vagus branches. 



20 Human embryo, 10.1 mm. in length, 623 — 11 — 2 — 4X240. Transverse sec- 

 tion through roots of lungs showing primordia of pulmonary plexuses, pp, cell 

 aggregates in pulmonary plexuses; vb, vagus branches. 



220 



