l""lg. 20 Transverse section from embryo in whic-li I lie somites aie forming, 

 hut no enniiiletc intersoniitie cleft has appeared, ('oluml)ia Coiled ion .\o. 'wd. 

 slide 3, row 4, section (>, X 30(). Reduced ]. 



1 lOctoderm 4 Hyperentodernial mesenchyme and 



2 Mesodorin incipient blood islands 



3 Entoderm o Coelom 



75 



