CH. IT. i 



KARYOKINESIS. 



21 



prominent. The division of the cell protoplasm into two 

 parts around the two nuclei begins in the diaster stage, and 

 is complete in the stage represented in fig. 25. 

 The karyokinetic process has been watched in all its stages by 

 more than one observer. The time occupied varies from half an 

 hour to three hours ; the details, however, must be studied in 

 hardened and appropriately stained specimens. They are most 

 readily seen in cells with large nuclei, such as occur in the 

 epidermis of amphibians. 



The process varies a good deal in different animal and vegetable 

 cells ; such as in the number of chromosomes, and the relative 



' s.-parat 

 cellar 



Antipole of daughter 

 nucleus. 



Remains of spindle. 



., Lighter substance of the 

 -* nucleus. 



Cell protoplasm. 

 - Hilus. 



fig. 25. Final stages of karyokinesis. In the lower daughter nucleus the changes are 

 still more advanced than in the upper. ( Waldeyer.) 



importance of the different stages. All attempted here has been 

 to give an account of a typical case. The phases may be sum- 

 marised in a tabular way as follows (from Quain's Anatomy) : 



NETWORK OR RETICULUM ... 1. Resting condition of mother nucleus 



(fig. 19). 

 2. Close skein of fine convoluted fila- 



OR SPTWFM 

 UJS D"1BCM 



ments (fig. 20). 



^ o /i i n A^ i ^?i 



: 3. Open skein of thicker filaments. 

 Spin 



Spindle appears (fig. 21 A). 

 CLEAVAGE ......... 4. Movement of V-shaped chromo- 



somes to middle of nucleus, and 



each splits into two sister threads 



(fig. 21 B). 

 STAR OR MONASTER ..... 5. Stellate arrangement of V fila- 



ments at equator of spindle (fig. 



22). 

 <'.. Separation of cleft filaments and 



movement along fibres of spindle 



(fig. 24 A and B). 



7. Conveyance of V filaments towards 



poles of spindle (fig. 24 C). 



8. Open skein in daughter nuclei. 



!>. Close skein in daughter nuclei (fig. 



25). 



10. Resting condition of daughter 

 nuclei (fig. 25). 



DIVERGENCE OR METAKINOI- 



DOUBLE STAR OR DIASTER . 



DOUBLE SKEIX OR DISPIREM 

 NETWORK OR RETICULUM . 



