124 THE STRUCTURE OF THE FOWL 



the circumstance that the coelome is not 

 hmited to the embryo, but also invades 

 extra-embryonic territory, it follows that the 

 stalk consists of two tubes, one within the 

 other. The outer tube forms a connection 



amn. 



Fig. 66. — Diagram showing the Mode of Development of the 

 Embryonic Membranes. Early stage. 



ch., chorion; amn., amnion); y.s., yolk-sac. 



between the somatopleure or body- wall of the 

 embryo and the extra-embryonic somatopleure. 

 The inner tube connects the yolk-sac with 

 the intra - embryonic part of the splanchno- 

 pleure, i.e. with the primitive gut (Fig. 64). The 

 space between the two tubes is a part of the 



