94 THE EMBRYOLOGY OF THE HONEY BEE 



while in Donacia the "primary dorsal organ" is formed prior to 

 the formation of the germ layers. In respect to other insects 

 little can be said that is not pure conjecture, since the data afforded 

 for comparison are too scant. To those familiar with insect em- 

 bryology comparisons with "the micropylar organ" (Wheeler 

 1893) or "procephalic organ" (Claypole 1898) of Anurida and the 

 "indusium" of Xiphidium (Wheeler 1893) will suggest them- 

 selves, but only further investigations on the embryology of 

 insects with special regard to the question as to whether a vestigial 

 "dorsal organ" is of frequent occurrence in insect embryos can be 

 of real value in determining the homology of these various anoma- 

 lous structures. 



