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 ABC, bounded by the heavy black 



m 



Fig. ^. — Dia^am to s^iow mode of fission of the apical cell, as seen from above. 

 /, the cell A, B, 0, divided by the partition 1 ; II, the fame cell with a second par- 

 tition, 2 ; III, the same cell with a tliird partition, 3. 



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

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



divided by th^ partition 2, II. ; 

 later, a third partition (3, III.) 

 is formed, and so on. ^t 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 

 faha) furnish a good illustration 

 of fission in the highest plants. 

 In this case, and in many 

 other, if not all, Dicotyledons, 

 the division takes place directly 

 .^'s-.38.-Meristem-ceiiBof the stem through the Centrally placed 



of Viciafaba, in process oJ liRSKtn ; in <=> ^ ■*■ 



the cells a, a, the process is in its nucleUS (a. Fig. 28 ). After the 



earlier stage ; at d it is completed. X- .1.1 n t. 



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 

 and k). 



