i6 



AAA TOM V AND MORPHOLOGY OF INSECTS. 



The lateral and dorsal regions of the embryo are ultimately 

 enclosed by the extension of the edges of the primitive band 

 over the whole yelk, tlius forming a somatopleure, or body- |j 

 wall. 



The embryo is usually, perhaps always, provided with an 

 amnion (Fig. 2, a, a'), developed like the amnion of vertebrates 



Fig. 2. — A longitudinal and two transverse sections of the embryo in the egg eight 

 hours after impregnation. The plane of the left-hand lower figure is indicated 

 by the line xx', and of the right-hand figure byjj^'' in the longitudinal section ; 

 a', outer layer, a, inner layer, of the amnion; cf., epiblast ; sf., stomodceum ; 

 me., mesoblast ; h., hypoblast ; //'., proctodaeum ; v., vitelline spherules ; d. p., 

 dorsal plate covering the blastopore ; tii., Malpighian vessel. All these figures are 

 drawn from actual sections. 



from the epiblast, and commencing as a reduplication of the 

 margin of the somatopleure of the embryo. It also connects 

 the somatopleure with that portion of the blastoderm which 

 covers the dorsal surface of the yelk behind the blastopore. 

 So far, the account I have given of the development of the 



