ORIGIN OF THE MITOTIC FIGURE 



75 



plasm. These investigators agreed that the amphiaster is formed 

 under the influence of the centrosome, which by its division creates 

 two new "centres of attraction" about which the astral systems arise, 

 and which form the foci of the entire dividing system. In them are 

 centred the fibrillae of the astral system, toward them the daughter- 



F 



Fig. 28. - Metaphase and anaphases of mitosis in cells (spermatocytes) of the salamander. 

 [Druner.] 



E Metaphase. Tlie continuous central spindle-fibres pass from pole to pole of the spmdle 

 Outside them the thm layer of contractile mantle-fibres attached to the d.vKlcd ^^^'-:^'^^''^^'^} 

 which only two are shown! Centrosomes and asters. F. Transverse section ^ -- ^ \ ^^ "^ !?^ J 

 figure showing the ring of chromosomes surrounding the central spmdle. the cut ^^'^^/^^ ' rL'''!"^/ 

 a;peanng as ''dots. G. Anaphase; divergence of the ^»-^g'^^--f-°"--"\^.^- ^j^J^^^ "S„f^,^^^ 

 tral spin5leas the interzonal fibres; contractile fibres ^vn^^^'^-\^or..^-' \ '^Xj^^^^^^^ 

 shown. H. Later anaphase (dyaster of Flemming) ; the central spmdle uly exposed to Mev. 

 mantle-fibres attached to the chromosomes. Immediately aftenvard the cell d.vdes (see P .g. ^) . 



chromosomes proceed, and within their respective spheres of influ- 

 ence are formed the resulting daughter-cells. Both Van Beneden and 

 Boveri fully recognized the importance of then" discovery. "We are 

 justified," said Van Beneden, ^ in regarding the attraction-sphere with 

 its central corpuscle as forming a permanent organ, not only of the 

 early blastomeres, but of all cells, and as constituting a cell-organ equal 



