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HAROLD R. HAGAN 



which might not be supported by tabulating a larger number of 

 cases. The embryos passing around the left side of the egg 

 presented no discoverable differences from the former class. 

 Embryos of eggs adjoining each other in the ootheca passed 

 around the same or opposite sides of the yolk mass indifferently. 

 The gravitational position of the ootheca had no influence in 

 regulating this movement as was determined by a study of a 

 number of oothecae in various positions. 



This movement was incidentally mentioned by Giardina ('00) 

 in his general account of the development of Mantis religiosa. 



Text fig. 1 Diagram to illustrate the movement of the embryo from the ven- 

 tral to the dorsal surface of the egg. A, ventral yolk. Embryo with characteris- 

 tic curvature which immediately precedes revolution. B, lateral aspect showing 

 embryo about one-third around. C, same view, but embryo about two-thirds 

 advanced to dorsal yolk. In this instance the posterior end of the embryo has 

 moved faster than the cephalic end so that its axis is parallel with that of the egg. 

 D, dorsal yolk. The embryo remains ventral side up until after emergence from 

 the ootheca. d, dorsal surface; v, ventral surface of the egg. 



