Plate X. 



Fig. G8. This embryo shows the result of au iujury made ou au uuin- 

 cubated blastoderm, at about twenty degrees to the right of the median 

 line on the boundary between the areas opaca and pellucida. The egg 

 was incubated for forty hours. The arrow shows the path traversed by 

 the mass of injured cells, as indicated by the small groups of dead cells. 

 The posterior end of the embryo is bent to the right. The curvature is 

 due doubtless to unequal growth of the cells on the tvi^o sides. (For a 

 transverse section through the injured region of this embryo, see Fig. 61). 

 X20. 



Fig. G9. The operation was of the same nature as the preceding, except 

 that it was made about thirty degrees to the right of the axial line instead 

 of twenty. The egg was incubated for twenty-four and one-half hours, and 

 the injury is situated slightly more posteriorly than in the preceding experi- 

 ment. X 25. 



Fig. 70. In this embryo the injury was made between three and four 

 hours after incubation had begun, at about forty-five degrees to the right 

 of the axial line on the boundary between the areas opaca and pellucida. 

 The egg was then incubated for thirty-six hours. The embryo is normal 

 in every way and the injured spot is in the vascular area, about half way 

 between the shvus tcrminalis and the pellucid area. X 18. 



Fig. 71. The injury in this blastoderm was made on the posterior margin 

 forty-five degrees to the right of the median line. The operation was per- 

 formed thirty-three and one-half hours after fertilization, and the egg was 

 then incubated for thirty-six hours. The group of injured cells has been 

 brought into the axis of the embryo, x 21. 



