112 



THE PLANT CELL, 



{j3) The Metaphase. — This phase commences by the separation 

 of the two halves of each longitudinally split chromosome, the 

 bends being the first portions to come apart; the free-ends 

 remain in contact for some time, but at last, by the agency of the 

 mantle-fibres, these are drawn asunder. The appearance now 

 presented is that of two systems of so-called secondary or 

 daughter-chromosomes travelling away from one another, there 

 being an equal number of loops in each system (see Figs. 87, 88). 





§$^^^MM^ 





Fig. 87. — Two Cells from AUmm Root-tip, showing the early raeta- 

 phase and late metaphase respectively. Note the cone-shaped 

 bundles of mantle-fibres in the left-hand cell. 



In surface view, or in slightly oblique sections of the cell, it is 

 now possible to make out two " rosettes " of chromosomes ; 

 between these are to be seen certain fibres of the achromatic 

 spindle which persist until the cell-plate has been formed, and 

 even after this. These fibrils are composed of the so-called 

 interzonal fibres, and are not contractile in nature. 



The later metaphase shows the two systems of secondary 



