GERM CELLS IN THE ARTHROPODA 139 



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 division 

 among the oogonia, or spermatogonia. Three stages 

 in the direct division of nurse cell nuclei in Leptinotarsa 

 decemlineata are shown in Fig. 8, a-c. Oogonia 

 and spermatogonia, however, do not exhibit such 

 clearly defined stages and after examining my prep- 

 arations 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 surrounded 

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

 could not be attributed as well or better to mitotic 

 phenomena. 



CONCLUSION. From the evidence at present 

 available we must conclude that amitotic division 

 of the germ cells has not been demonstrated, and 

 that not until such a process is actually observed 

 in living cells will any other conclusion be possible. 



There are still two questions regarding the germ- 

 cell cycle in beetles that we shall attempt to answer ; 

 (1) Does a chromatin-diminution process occur 

 such as has been described in Miastor and Ascaris? 

 and (2) Is the segregation of the germ cells controlled 

 by the nuclei or by the cytoplasm ? 



The fact that part of each chromosome is cast out 



