Nerve cord 

 ndoderm 

 Archenteron. 



Fig. A 



Fig. B 



Nerve cord 

 Notochord 

 Mesoderm, 



'Ectoderm 



Endoderm 

 rchenteron- 



Nerve cord- 



' 'otochord^ 



Epimere. 



Fig. C 



Fig. K 



Longitudinal Section Through Stage "C 



Dissected Embryo at Stage "C" 



Fig. 6. Organogenesis in Amphioxus. Diagrams A to I are cross sections 

 to show the development of the continuous nerve cord and notochord, 

 and the discontinuous enterocoels. Drawing J is a horizontal section. 

 Drawing K has the outer ectoderm dissected away to show the relationship 

 between the archenteron and the enterocoels. 



