226 THE EMBRYOLOGY OF THE HONEY BEE 



ginating oesophageal wall ; at least this is the impression given by 

 the sections studied, in which the peripheral part of the torn mem- 

 brane is seen still attached to the wall of the mid-intestine ( Fig. 

 896). A similar pro ventricular valve appears to be formed in 

 much the same way in Forficula and Periplaneta (Heymons, 



1895)- 



'-.Oe 



Mint 



OeVIv 



FIG. 89. Sagittal sections through the junction of the fore and mid- 

 intestines of two embryos, showing the formation of the oesophageal 

 valve (OeVIv). A, Stage XIV; B, Stage XV, x 567. 



At the time of its first appearance the stomodaeum occupies a 

 position corresponding to the cephalic pole of the egg, and during 

 its earlier stages its lumen coincides with the long axis of the egg. 

 At Stage X the embryo begins to shorten, drawing the external 

 opening of the stomodaeum the future mouth to its final posi- 

 tion on the ventral surface of the egg, the oesophagus therefore 

 acquiring a curved course. At the same time the hypodermis 

 forming the angle bounding the future mouth on its morphologi- 



