Fig. 5 Transverse section of an embryo of two somites at the level indi- 

 cated in Figure 3. Slide 5, row 1, section 6, X 300. Reduced j. 



1 Ectoderm 5 Hyperentodermal mesenchyme 



2 Mesoderm 6 Coelom 



3 Entoderm 7 Neural plate 



4 Hypectodermal mesenchyme 



Fig. 6 Dorsal view of model of mesoderm (white), mesenchyme (green) and 

 vasofactive cells (yellow) of an embryo of four somites. Columbia collection No. 

 409, X 300. Reduced \. 



1 Somite 1 4 Site of quintal ganglion 



5 Endothelial anlage opposite the 



Somite 1 



Anlages of juxta-neural anastomosis 

 Connection between the j uxta-neural 

 anastomosis and the aorta, cf. fig- 

 ure 25 



second nephrotome; cf. figures 8 

 and 9 

 Region of cardiac coelom 



60 



