70 



EARLY EMBRYOLOGY OE THE CHICK 



in Figure 28, C. The heart here is enlarged and displaced 

 somewhat to the right of the mid-line but its fundamental 



neural plate ectoderm 

 dorsal mesoderm 



notochord 



superficial ectoderm 

 neural groove 



— somatopleure 

 1 splanchnopleure 



splanchnic mesoderm 



gut imtnediately caudal to 

 anterior intestinal portal 



-f 



'■iJ 



dorsal mesoderm 



epi-myocardium 



neural groove 



endocardium -^ g^t immediately caudal to 

 anterior intestinal portal 



) somatopleure 



y splanchnopleure 



epi-myocardium 

 endocardium 



3- 



dorsal mesoderm 



fore-gut 



epi-myocardium 



endocardium 



line of fusion of lateral margins of 

 anterior intestinal portal 



^ 



nl 



Tt 



V 



Fig. 26. — Diagrams of transverse sections through the pericardial region 

 of chicks at various stages to show the formation of the heart. For location of 

 the sections consult Fig. 27. 



A, at 25 hours; B, at 26 hours; C, at 27 hours; D, at 28 hours; JS, at 29 hours. 



relations are otherwise the same as in a 29-hour embryo (Fig. 

 26, £). 



