6 4 



CHANGE IN CELL-PROTOPLASM 



of longitudinal bands of chromatin arranged along the 

 meridians of the nuclear spindle (c). 



While this is going on the network of the cell-protoplasm 

 undergoes a change, some of its fibres becoming arranged in 

 the form of two radiating bundles of filaments one at each 

 pole of the spindle (B, c). And at about this stage (c) the 



FIG. 10. Stages in the binary fission ot an animal cell. 

 A c, formation of the nuclear spindle and breaking up of the chro- 

 matin coil (black). 



D, E, aggregation of the chromatin at the equator of the spindle. 



F, fission of the chromatin-masses. 



G, accumulation of the chromatin at the poles of the spindle and 

 ormation of the cell-plate. 



H, reconstruction of the daughter-nuclei. (After Carnoy.) 



nuclear membrane disappears so that the cell-protoplasm 

 mingles with the nuclear protoplasm or achromatin. 



Next the longitudinal bands of chromatin gradually con- 

 centrate at the equator of the spindle, where they form a 

 ring of somewhat elongated masses (D). Each of these 

 undergoes a splitting, and may thus become ring-like (E) ; 



