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. 

 89B). A similar proventricular valve appears to be formed in 

 much the same way in Forficula and Periplaneta (Heymons, 



I895). 



OeVIv 



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

 intestines of two embryos, showing the formation of the oesophageal 

 valve (OcVlv). 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- 



