HYMENOPTERA 331 



similar to those of the cleavage cells. A little later, irregular mitotic 

 figures are found. These are usually minute and have the appearance of 

 being in some cases multipolar and in others unequal. Multinucleate 

 cells soon become abundant, some of them being of large size. Degen- 

 eration of the nuclei of the yolk cells soon becomes frequent, such nuclei 

 diminishing in size and finally becoming reduced to minute deep-staining 

 spherules which leave the cell body and enter the yolk. Secondary yolk 

 cells are formed by the immigration of nuclei from the blastoderm into 

 the yolk. These soon are indistinguishable from the primary yolk cells. 

 Yolk cells are found distributed through the yolk until shortly before 

 hatching. They are frequently seen clustered under the epithelium of 

 the mid-gut, during the time when the latter is engaged in covering the 

 lateral faces of the yolk. Yolk cells and yolk disintegrate at the time of 

 hatching, being presumably digested. 



The total time normally required for the development of the egg is 

 76 hours. This is divided approximately as follows: cleavage, 14 to 16 

 hours; formation of the blastoderm, 1-1 to 16 hours; formation of meso- 

 derm, rudiments of mesenteron, and embryonic envelope, 12 to 14 hours; 

 remainder of development, including differentiation of tissues and 

 organs, 32 to 34 hours. The earher stages, including the formation of 

 the germ layers, the serosa, etc., occupy considerably over one-half the 

 time required for total development. 



A detailed account of the embryology of the honeybee is to be found 

 in a monograph by Nelson (1915). 



References 



Hymenoptera: Bischoff (1928), Blochmann (1884, 1886), Brandt (1878), Carriere 

 (1886), Gatenby (1918), Leiby (1926), Marchal (1897), Stuhlmann (1886), Whiting 

 (1937). Ageniaspis fusdcollis; Silvestri (1906a, 19086). Anaphoidea luna; Silvestri 

 (1915). Apanteles sp.; Mukerji (1930). A. glomeratus; Grandori (1911), Hegner 

 (1915). A. thompsoni; Vance (1931). Apis mellifica; Blochmann (1887, 1889), 

 Btitschli (1870), Dickel (1901, 1902, 1904), Graber (18886), Grassi (1884), Hegner 

 (1915), Kowalewsky (1871), Nachtsheim (1913), Nelson (1912-1915), Petrunke- 

 witsch (1901, 1903), Schnetter (1934), Siebold (1856), Snodgrass (1925). Azteca sp.; 

 Strindberg (19166). Banchus jemoralis; Bledowski and Krainska (1926). Biorhiza 

 aptera; Weismann (1882). Bombus sp.; Weyer (1928). B. terrestris; Korschelt 

 (1886). Camponotus sp.; Blochmann (1892), Strindberg (1913a), Weyer (1928). 

 C. herculeanus; Hegner (1915). C. ligniperda; Hecht (1924), Reith (1931), Strindberg 

 (19136). Cephus cinctus; Smith (1938). Chalicodoma muraria; Carriere (1890), 

 Carriere and Burger (1897), Wheeler (1898). Copidosoma sp.; Hegner (1914), 

 Howard (1919), Leiby (1929). C. buyssoni; Silvestri (1910). C. gelechiae; Hegner 

 (1915), Leiby (1922). C. tortricis; Howard (1925), Patterson (1915). C. trunca- 

 tellum; Hegner (1915), Leiby (1922). Dinocampus rutilis; Jackson (1928). Encarsia 

 partenopea; Silvestri (1915). Encyrtus sp.; Howard (1906). E. aphidivorus; Silvestri 

 (19086). E. fuscicollis; Bugnion (1891), Marchal (1898, 1899, 1904), Martin (1914). 

 E. mayri; Silvestri (1915). E. testaceipes; Marchal (1904c). E. variicornis; Howard 

 (1919). Formica sp.; Ganin (1869), Graber (18886), Strindberg (1913a), Weyer 



