64 EMBRYOLOGY OF INSECTS AND MYRIAPODS 



dorsal surface of the embryo into a spatially and mechanically more 

 favorable position, whereas no apparent advantage is attained in the 

 grasshopper. In Platycnemis Seidel (1929) reports that prevention of 

 blastokinesis by constriction seemingly inhibits development of a pos- 

 terior part of the embryo beyond the differentiation of the organ sj^stems; 

 whereas if the anterior part of the embryo develops in front of an incom- 

 plete constriction, blastokinesis occurs in that part of the egg, and 

 histological differentiation is completed. Accordingly it seems that 

 blastokinesis is prerequisite for the completion of development in 

 Platycnemis. 



References 



Baker (1921), Brandt (1869), Butt (1934, 1936), Cole and Jahn (1937), Ganin 

 (1869), Graber (1878, 18886), Grimm (1870), Hagan (1917), Heymons (18946, 1905), 

 Johannsen (1928), Kupffer (1866), Miller (1939), Muir and Kershaw (1912), Nelsen 

 (1931), Nelson (1912), Nusbaum (1890a), Poluszynski (1911), Scheinert (1933), 

 Seidell (1929), Slifer (1931a, 1932o, 1934, 1937, 1938), Strindberg (1915e), Tirelli 

 (1931), Waddington (1935), Wagner (1894), Wheeler (1890), Willey (1899). See 

 also the list of general works cited in Chap. II. 



