Structure and Division of the Vegetahle Cell. 199 



stoma, from base to apex of the leaf, but transversely. 

 Though failing to obtain in Ornifhogalum a good instance 

 of nuclear division, this has been afforded by Scilla hifolia, 

 the nuclear disc, when fully established, being nearly as 

 large as either of the elongated daughter-nuclei. In the 

 surface growth of the leaf epidermis, however, it is, to a far 

 greater extent, by elongation of cells which had been cut 

 oil' in a young state, rather than by actual multiplication, 

 that a greater extent of surface is produced. Now, as these 

 cells, after multiplication and elongation, pass more and 

 more iuto the permanent state, division of the nucleus, with 

 subsequent formation of a cell-plate, is correspondingly rare ; 

 but just as in the guard-cells of the stoma, so here also 

 the nucleolus and nucleolo-nucleus still display a greater 

 reproductive activity, and, as a result, we may find all 

 stages in the dumb-bell shaped division of the nucleolus, 

 which seems now to pass through this change much more 

 sluggishly than in embryonal cells. We therefore find many 

 cell nuclei with two well-marked nucleoli, and one, two, 

 or more nucleolo-nuclei in each. This exactly coincides 

 with the cells of the suspensor of some Lcguminosce at a 

 certain period, as described by Hegelmaier ; but, whereas, 

 in all the examples of Scilla examined only one nucleus 

 was in each cell, in those of the Leyuminosce the nuclei 

 were still able to divide, each resulting daughter nucleus 

 carrying with it a nucleolus. This latter state of affairs 

 is, I think, simply a progression on the first, in which the 

 nuclei, as well as nucleoli, go on dividing, without, how- 

 ever, being seemingly able to form septa. 



I will now deal very shortly with the ordinary pallisade 

 parenchyma cells of the leaf, as in all essential points they 

 do not differ from those already described. If we take a 

 portion of young epidermis to which patches of these cells 

 are adhering, we immediately notice all steps in the cycle, 

 such as has already been discussed. Some of these cells 

 will contain a nucleus, nucleolus, and nucleolo-nucleus ; 

 others a nucleus, nucleolus, and two nucleolo-nuclei, 

 others, again, a nucleus, two nucleoli, wnth a nucleolo- 

 nucleus in each, while nuclear division may be seen pro- 

 ceeding or completed, each daughter nucleus carrying with 

 it a nucleolus (Plate IX. figs. 12-15). This is there« 



