152 DEVELOPMENTAL CHANGES IN THE EARLY EMBRYO 



Rhombocoel 



Rhombencephalon 



Endolymphatic duct 



Otic vesicle 



Branchiol vessel 



Bronchial (gill) cleff 

 Opercular (gill) chamber 



Neurocoe 

 Nerve cord 

 Notochor 



Pronephric tubule 

 Coelon^ 



Bulbus arteriosus Ventricle 



2 



Nerve cord 



Dorsal aorta Notochord 



Dorsal oorto-y 



Foregut 



Midgut- 

 Somotopleure- 

 Splanchnopleure- 



Lateral line nerve 

 Aortic arch 



Pronephric duct 

 dgut 

 Coelom 



Proctodeum 



Representative transverse sections of an 8 mm. frog larva. 



