138 GERM-CELL CYCLE IN ANIMALS 



regions of the insect ovary and, since Payne (1912) 

 has shown that in Gelastocoris the cells that appar- 

 ently multiply amitotically do not produce ova, it 

 seems safe to conclude that in Protenor the ova are 

 not descended from cells that divide amitotically. 



Amitotic division of germ cells followed by mitotic 

 division has been described by Wieman (19106, 

 1910c) in the ovaries and testes as well as in the nurse 



Fig. 43. — Stages in amitosis in spermatogonium of Leptinotarsa signa- 



ticollis. {From Wieman, 1910.) 



cells of a chrysomelid beetle, Leptinotarsa signati- 

 collis. Germ cells in both ovary and testis taken 

 from full-grown larvae were found in stages of divi- 

 sion recognized by Wieman as amitotic (Fig. 43). 

 It was difficult to demonstrate actual division of 

 the cytoplasm, but that such a division really occurs 

 was inferred because binucleated cells apparently 

 gave rise to spermatocytes with single nuclei. Rapid 

 cell division is assumed by Wieman to account for 

 amitosis. This is brought about by fluctuations in 

 the nutritive supply or, in the case of the testis, by 

 the rapid proliferation of cells during the formation of 

 cysts. 



