PLATE 2 



EXPLANATION OF FIGURES 



16 Human embryo, 10.1 mm. in length, 623—16—3—7X160. Transverse 

 section through abdominal region showing primordia of sympathetic trunks and 

 prevertebral plexuses, a, aorta; jpv, prevertebral plexuses; Sy, sympathetic 

 trunk. 



17 Human embryo, 10.1 mm. in length, 623 — 15 — 2 — 2X160. Transverse sec- 

 tion through upper abdominal region showing primordia of sympathetic trunks 

 and prevertebral plexuses, a, aorta; pv, prevertebral plexuses; Sy, sympathetic 

 trunk. 



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