Stom 



Meso 



Meso 



AMR 



PMR 



""Ect 



Meso 



FIG. 87. Anterior (A) and posterior (B) ends of a median sagittal 

 section through an embryo, Stage VIII, showing the anterior (AMR) 

 and posterior (PMR) mesenteron rudiments, which are a'bout to unite on 

 the dorsal surface of the egg. The stomodaeal invagination (Stom) is 

 just appearing. The relation of this to the anterior mesenteron rudiment 

 is clearly shown, x 243. 



