218 Mr J. M. Macfarlane on the 



Figs. 3a, 3h. Nuclei isolated, and exhilnting changes prepara- 

 tory to division. At this time the nucleolo-nucleus probably divides. 

 From Mr Jackson's cabinet. 



Fig. 4. Single cell, with nucleus, (fee, alone shown. The nucleo- 

 plasm has been expelled on each side of the nucleolus through the 

 nuclear membrane, but is still connected with the nucleolus by 

 delicate threads. 



Fig. 5. Single cell, with nucleus, &c., alone shown. Tbe nuclear 

 membrane has fused with the nucleoplasm at the poles. 



Fig. 6. Single cell, with nucleus, &c., alone shown. The nucleolus 

 is now dividing, the forming daughter nucleoli being still connected 

 by delicate threads. Crossing the diameter of the cell is a row of 

 granules embedded in the peripheral protoplasm of the cell. 



Fig. 7. Single cell, with nucleus, &c., alone shown. The daughter 

 nucleoli are now retreating along the nuclear barrel, and in their 

 course scatter its filaments. 



Fig. 8a. Single cell. The daughter nucleoK have now reached 

 the polar masses of nucleoplasm, which for a time had been driven 

 before them. 



Fig. 85. Isolated nucleus showing appearances at this period. 

 From Mr Jackson's cabinet. It will be observed that a nucleolo- 

 nucleus has been detected in most of the nucleoli hitherto. 



Fig. 9. Complete cell with peripheral protoplasm, chlorophyll 

 bands, &c. The single row of granules has now increased to 

 an irregular band, and among the granules the septum will soon 

 form. The barrel has greatly increased in width. 



Fig. 10. The septum is now laid down as a narrow circular rim 

 inside the wall, and the peripheral jDrotoplasm is infolding as growth 

 of its edge continues. 



Fig. 1 la. The septum has now grown in and united with the outer 

 edge of the nuclear barrel, and will pass in between the halves of the 

 cell plate. 



Fig. lib. Isolated nucleus septum with attached and projecting. 

 The nuclear barrel is now about to wane. From Mr Jackson's cabinet. 



Fig. 12. Portion of cell with ingrowing septum. The chloro- 

 phyll bands, previous to fission, are being slightly pushed in. 



Fig. 13. The septum has increased to a deep shelf, while a co- 

 incident waning of the nuclear barrel has taken place. 



Fig. 14. The septum is nearly completed, the nuclear barrel 

 being now reduced to a narrow irregular band. 



Fig. 15. The septum is here completed, and only a filament or two 

 remain as relics of the nuclear barrel. 



