VIIl] 



OF THE GROWING POINT 



639 



that of division, the less abrupt will be the alternate kinks or 

 curvatures of the portions which lie along the axis, and the more will 

 these portions appear to constitute a single unbroken wall. 



(3) But an appearance nearly, if not quite, indistinguishable 

 from this may be got in another way, namely, when the original 

 growing cell is so nearly hemispherical that it is actually divided 



Fig. 285. Section of growing shoot 

 of Selaginella, diagrammatic. 



Fig. 286. Embryo of Jungermannia. 

 After Kienitz-Gerloif. 



by a vertical partition into two quadrants, and when from this vertical 

 partition, as it elongates, lateral partition-walls arise on either 

 side. Then, by the tensions exercised by these, the vertical partition 



Fig. 287. 



will be bent into little portions set at 120° one to another, and the 

 whole w^ill come to look just like that which, in the former case, was 

 made up of parts of many successive obhque partitions (Fig. 287). 



Let us now, in one or two cases, follow out a httle further the 

 stages of cell-division whose beginnings we have studied in the 

 last paragraphs. In the antheridium of Riccia, after successive 

 obhque partitions have produced the longitudinal series of cells 

 shewn in Fig. 284, 4, it is plain that the next partitions will arise 

 periclinally, that is to say parallel to the outer wall, which coin- 

 cides with the short axis of the oblong cells. The effect is to produce 



