354 



RICHARD E. SCAMMON 



amount of yolk present by which the original tube of entoderm is 

 spread out plate-like upon an almost flat surface of the yolk sub- 

 stance. In such a case the ventral portion of the original tube 

 would form the peripheral portion of each lateral half of the plate 

 and the folding of the plate into a tube again in the course of 



•\N. 





Hep.d 



Fig. 13 Transverse section of an Acanthias embryo 4.8 mm. long (H.E.C. 

 1398), showing the effect of the inclination of the embryo upon the lateral hepatic 

 diverticula. X 50. Hep.d., hepatic diverticula. 



the separation of the embryo from the yolk would approximate 

 once more the two separated parts. These lateral diverticula 

 may then be regarded simply as the potential halves of an original 

 ventral pouch which begin their expansion before their union 

 along the ventral median line takes place. As might be expected 



