CELLS AND TISSUES 

 How Plant Cells Divide 



III 



Both plant and animal cells are said to divide by a proc-ss c,f n-ll 

 division called mitosis. In plants, the resting cell has a nuclcM.. wl,i,-l. 

 contains a network of linin fibers, on the strands of which are f,.,n„l 

 irregular chromatin granules. When the cell is activated to divide 

 these granules assume the form of a thickened, irregularly coiled thread' 

 called a spireme. This thread splits lengthwise into two thr(.-„is 

 which remam so close together that for some time they appear as 

 one, finally splitting crosswise into a number of chromo.sonus that 



resLind 

 cell ^ 



prophets e. metapWe 



anaphase telophase 



Mitosis in plant cells. Read the text and ('\|)laiii the (li;i;:r;iiii 



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are constant in number in all cells of a given species. While this proc- 

 ess is going on there has appeared in the cytoplasm on oj)j")osite sides 

 of the nucleus two caplike masses of delicate fibers, which later will 

 give rise to the so-called spindle fibers. Now the iiuchar membrane 

 disappears and the fibers grow into the center of the nucleus, where 

 some become attached to the chromosomes while others join with 

 fibers from the opposite side or pole. This series of changes is 

 known as the prophase. These two cone-shapetl ma.s.ses of fibers 

 form the spindle, while the split chromo.somes arrange themselves 



