654 



EMBRYOLOGY : CHICK 



tn.b 



vt.v. 



ni.b. 



spp. 



per c. 



vt.v. 



sp.o 



B 



Fig. 512. — The chick embryo at the thirty-sixth hour of incubation. — From 

 Marshall and Hurst, Junior Course of Practical Zoology. 



A , A dorsal view ; B, a diagram of a median longitudinal section. 



al.v., Rudiment of the outgrowth of the future wall of the gut which will form the allantois ; am., amnion, 

 beginning to cover the head ; au., pit which will form auditory vesicle ;f.b., fore-brain ; h.h., hind-brain ; 

 hy., endoderm ; m., myotome ; tn.b., mid brain ; n.h., notochord ; neu., pit representing the neurenteric 

 car al ; o.v., optic vesicle ; p.s., primitive streak ; per.c, portion of coelom which will become pericardial 

 cavity ; ph., pharynx ; sp.o., spinal cord ; spp., splanchnopleure ; sop., somatopleure ; v., ventricle; 

 vt.v., vitelline vein. 



