EARLY DEVELOPMENT 47 



Grassi and others on comparative anatomical grounds and Heymons 

 (1895a, 18986) on ontogenetic evidence considered that the gonopophyses 

 represented specially developed structures which could not be referred to 

 former limbs. Later writers with few exceptions, in agreement with 

 Verhoeff, believe that the lateral divisions of the eighth and ninth sternal 

 plates in the Thysanura represent flattened leg coxae, the gonocoxites, 

 whereas the ovipositor lobes borne mesally by these structures, a pair 

 each by the eighth and ninth gonocoxites, represent modified distal leg 

 segments. In the pterygote insects, then, the anterior ovipositor valves 

 of the eighth segment and the inner valves of the ninth are believed to be 

 serially homologous structures and to correspond to the telopodites of 

 Thysanura, the lateral ovipositor valves of the ninth segment being 

 gonocoxites. The recent work of Nel (1929) on the development of the 

 terminalia of orthopterous females seems further to substantiate this 

 view. Nel also maintains that the common oviduct originates as an 

 unpaired ectodermal (epidermal) invagination and that there is no evi- 

 dence that part of the common oviduct is of mesodermal origin or that it 

 has a paired origin in the Orthoptera and in insects in general. 



References 



Reviews of the literature dealing with the germ cells of the Eutracheata, especially 

 of insects, have been published by Hasper (1911), Hegner (1914), and Nelsen (1934). 

 Some works which include this subject are the following: 



Myriapoda, Chilopoda: Heymons (1901). 



Collembola: Claypole (1898), Philiptschenko (1912). 



Thymnura: Heymons (1897). 



Orthoptera: Heymons (1895a), Nelsen (1934), Roonwal (1936), Wheeler (1893). 



Ephemerida: Heymons (1897). 



Odonata: Heymons (1897), Tillyard (1917). 



Dermaptera: Heymons (1895a). 



Homopiera: Balbiani (1870), Metschnikoff (1866), Shinji (1919), Strindberg 

 (1919), Tannreuter (1907), Todt (1933), Uichanco (1924), Walczuch (1932), Will 

 (1884, 1888), Witlaczil (1884). 



Heteroptera: Mellanby (1936), Seidel (1924). 



Lepidoptera: Eastham (1927), Johannsen (1929), Lautenslager (1932), Sehl (1931), 

 Schwangert (1905), Toyama (1902), Woodworth (1889) 



Coleoptera: Brauer (1925), Butt (1936), Friederichs (1906), Hegner (1908, 1914), 

 Heider (1889), Hodson (1934), Hirschler (1909), Inkmann (1933), Lecaillon (1898), 

 Paterson (1931, 1936), Saling (1907), Tiegs and Murray (1938), Wray (1937). 



Siphonaptera: Kessel (1939), Packard (1872). 



Diptera: Butt (1934), DuBois (1932), Escherich (1900), Gambrell (1933), Grimm 

 (1870), Hasper (1911), Hegner (1914), Huettner (1923), Kowalewsky (1886), Lassman 

 (1936), Metcalfe (1935), Metschnikoff (1866), Noack (1901), Pratt (1900), Ritter 

 (1890), Sachtleben (1918). 



Hymenoptera: Gatenby (1918), Hegner (1915), Henschen (1928), Leiby (1922), 

 Nelson (1915), Petrunkewitsch (1903), Silvestri (1907). 



Blastoderm, Germ-band Formation, Yolk Cells, Segmentation, and Appendages: Auten 

 (1934), Brandt (1878, 1880), Carriere (1891), David (1936), Fernando (1933), Folsom 



