246 



ROBERT W. HEGNER. 



TABLE IV. 



EXPERIMENTS IN KILLING PARTS OF EGGS IN THE BLASTODERM STAGE. 

 Leptinotarsa decemlineata Series L.D. 04. 



embryo is entirely missing. The conclusion is reached that the 

 part of the blastoderm which would have produced the abdomen 

 of the embryo was killed in the operation, and that none of this 

 region was regenerated by the tissue which remained alive. 



12 '* 



FIG. 12. Ventral view of an egg of Leptinotarsa decemlineata five days old 

 (L.D. 04 A2). The posterior end of the egg (&) was killed when in the blastoderm 

 stage (see Fig. 2) ; the blastoderm which remained alive produced a normal head 

 (h) and thorax (/). 



FIG. 13. Ventral view of an egg of Leptinotarsa decemlineata eight days old 

 (L.D. 04 A3), operated upon as in Fig. 12. Only a head (h) developed from the 

 tissue which remained alive. 



FIG. 14. Side view of an egg of Leptinotarsa decemlineata five days old (L.D. 

 04 63). The anterior end of the egg (fe) was killed when in the blastoderm stage 

 (see Fig. 2) ; the blastoderm which remained alive produced a normal abdomen (ab) 

 and part of the thorax (0. 



Fig. 13 was drawn from an egg that was fixed three days later 

 than that of Fig. 12, i. e., at the age of eight days. Only the 

 head of this embryo developed. It is apparent that not only 



