PLATE 7 
Amnion 
Branchial grooves 1- . 
g 3 Mandibular process 
Heart 
Body stalk 
Yolk-sac ; 
Maxillary process Mandibular process 
Branchial arch 2 
Branchial arch 3 
Cephalic flexure 
Cervical sinus 
Eye Atrium of heart 
Olfactory pit 
Yolk sac 
U pper limb 
bud 
Cut edge 
of amnion 
Mesodermal 
segment 
Lower 
limb bud 
Mesonephros 
Upper: Human embryo of 2.6 mm., showing yolk sac. Enlarged many 
times. After His, Normentafel 
Lower: Pig embryo of 6 mm. Compare with Plates 8 and 9. After 
Prentiss and Arey 
