MITOSIS 



"3 



a number of segments of equal length, which may be straight 

 and rod-shaped, or curved into a horseshoe shape, or may 

 be simply spherical or ovoid masses. In some cases the 



Fig- 23- 



Diagrams representing the essential phenomena of mitosis. A , a cell with resting 

 nucleus containing a chromatic reticulum and a single nucleolus. The 

 centrosome is double and surrounded by the centrosphere. £, the centro- 

 somes are separating and each is surrounded by astral rays ; the chromatin 

 forms a convoluted thread or spireme. C, The spireme is broken up into a 

 number of V-shaped chromosomes, the polar spindle is formed between the 

 now widely separate centrosomes. D, The chromosomes attached to the 

 spindle-fibres are arranged at the equator of the spindle. £, division of the 

 chromosomes, which are viewed end on. J^, divergence of the chromosomes. 

 G, chromosomes collecting at the poles of the spindle, the space between 

 them occupied by interzonal fibres ; commencement of division of the cell- 

 body. If, /, complete division of the cell, and reconstitution of the nuclei. 

 In / the centrosomes are dividing preparatory to a new mitosis. Note 

 ^./?=prophase ; £=metaphase ; IF, (7=anaphase. /f, /=telophase. 



curved rods may be joined together by their ends to form 

 rings. But their shape is relatively unimportant, the essential 

 thing is that the chromatin is resolved into a definite number 



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