114 C - M - CHILD. 



Nuclear division in the development of the female reproductive 

 organs of Moniezia cxpansa and M. pianissimo, is predominantly 

 amitotic though typical mitoses occur, their frequency varying 

 apparently in different chains and in different proglottids. 



After the long period of repeated amitotic division the nuclei 

 pass through the characteristic mitotic maturation divisions and 

 the cells form typical ova. 



The process of amitosis consists in the formation of a con- 

 striction in some part of the nucleus or of a "nuclear plate" or 

 membrane across some portion of the nucleus and the separation 

 of the nuclei thus marked off and later of the cytoplasm about 

 each. Each part thus separated usually possesses a visible 

 nucleolus at the time of formation of the membrane. 



The fact that the female germ-cells may arise by a long series 

 of divisions almost wholly amitotic is of considerable theoretical 

 importance. There is no room for doubt that the fate of a cell 

 may be the same, whether it divides mitotically or amitotically 

 during developmental stages. It is also very difficult to under- 

 stand how anything like individuality of the chromosomes can be 

 maintained in this case during the development of the germ-cell. 



The two forms of division may occur side by side in the same 

 tissue and at the same stage, but their relative frequency may 

 vary in different individuals and in different proglottids. It seems 

 probable, therefore, and other data will confirm this conclusion, 

 that the form of division is determined by the conditions to which 

 the cell is subjected. 



HULL ZOOLOGICAL LABORATORY, 

 UNIVERSITY OF CHICAGO, 

 August, 1906. 



