38 BOTANY. 



division. The triangular apical cells of the growing stems? 

 divide repeatedly in the manner shown in the diagram (Fig. 

 27). Here the cell A B C, bounded by the heavy black 



Fig. 27. Diagram to show mode of fission of the apical cell, as seen from above. 

 7, the cell A, , C, divided by the partition 1 ; //, the t-ame cell with a second par- 

 tition, 2 ; ///, the same cell with a third partition, 3. 



lines, is first divided into tAvo unequal portions by the parti- 

 tion 1, 1. ; next the larger portion of the divided cell is again ' 

 divided by the partition 2, II. ; 

 later, a third partition (3, III.) 

 is formed, and so on. It is no- 

 ticeable that in this case the 

 partition always forms parallel 

 to the oldest wall of the divid- 

 ing cell. By continued growth 

 the apical cell retains, despite 

 its repeated divisions, its origi- 

 nal dimensions. 



50. The growing cells of the 

 stem of the English bean ( Vicia 

 faba) furnish a good illustration 

 of fission in the highest plants. 

 In this case, and in many 

 other, if not all, Dicotyledons, 

 the division takec place directly 

 through the centrally placed 



Fig. 28.-Meri8tem-cells of the stem 

 of nciafaba, in procees of fission ; in 



the cells a, a, the process is in Us nucleus (a, Fig. 28). After the 

 earlier st age ; at b it is completed, x . * ' , 



300. After Pranti. formation of the new wall each 



new nucleus moves away and occupies a position on the 

 opposite side of the cell from where it was formed (as at J 

 and k). 



