STUDIES ON GERM CELLS 427 



however, claims that the cells which divide amitotically do not 

 produce ova but are degenerating or secretory. 



Foot and Strobell ('11) described in ovaries of Protenor, the 

 amitotic division of certain cells which later produce ova. There 

 is, however, considerable difference of opinion among investi- 

 gators as to the origin of the ova from the various regions of the 

 insecta ovary and, since Payne ('12) has shown that in Gelasto- 

 coris the cells which apparently 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 ('10b, '10c) in the ovaries and 

 testes as, well as in the nurse cells of Leptinotarsa signaticollis. 

 Germ cells in both ovary and testis taken from full grown larvae 

 were found in stages of division recognized by Wieman as ami- 

 totic. 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. 



I have studied my preparations of Chrysomelid beetles carefully 

 with the aim of detecting amitotic division and have observed 

 what appears to be direct nuclear division among the nurse 

 cells, but could not demonstrate with certainty this kind of divi- 

 sion among the ougonia, or spermatogonia. Three stages in the 

 direct division" of nurse cell nuclei in Leptinotarsa decemlineata 

 are shown in figure 67. Oogonia and spermatogonia, however, 

 do not exhibit such clearly defined stages, and after examining 

 my preparations and several slides kindly sent me by Doctor 

 Wieman I am forced to conclude that amitosis has not been 

 demonstrated. It is true that frequently dumb-bell shaped 

 nucleoli occur in certain of the nuclei and -frequently two nucleoli 

 are present at opposite ends. Also two nuclei may be sur- 

 rounded by a single cell wall, but no stages were present which 

 Could not be attributed as well or better to mitotic phenomena. 



