THE HIGHER CRYPTOGAM I A. 107 



gitudinal growth of the bud is produced exclusively by di- 

 vision of the apical eells, by means of septa at right angles 

 to the surfaces of the bud; the transverse septa which 

 appear in the apical cells are strictly vertical ; the fore 

 edge of the bud is a simple cellular layer. Afterwards, for 

 the first time, when the middle region has become more 

 and more thickened by the repeated formation of septa 

 parallel to the surface, and when this thickening has ad- 

 vanced close to the fore edge, the transverse septa appear in 

 the apical cells, inclined alternately upwards and downwards, 

 and parallel to the circumference of the bud. Thus the 

 form of longitudinal growth of the bud passes into that 

 which occurs in the shoots of older plants. 



The arrangement of the buds of Lunularia and of 

 Marchantia, with respect to the longitudinal axis of the 

 shoot upon which they originate, is a very constant one ; 

 their surfaces are always at right angles to that axis 

 (PL XV, figs. V, 19). Until their longitudinal growth is 

 almost completed, the buds are surrounded by a trans- 

 parent gelatinous mucilage. When the growth of the bud 

 in length and breadth is ended, the cell which supports it 

 dies and withers, and the bud becomes free. A. moist sub- 

 stratum outside the receptacle is all that is now necessary 

 for its further development. 



Under such circumstances some of the cells of its under 

 side first grow out into rootlets. Then new shoots begin 

 to be developed from the bottom of the lateral indentations 

 of the bud. The middle cell of the group which has been 

 so long arrested in its growth, and which is somewhat 

 larger than its neighbours, becomes the mother-cell of the 

 first new shoot (PI. XV, fig. 8). It divides by a transverse 

 septum, and the front one of the new cells by a longitudinal 

 septum. The division of the latter by laterally inclined 

 septa causes the further growth of the shoot, which pro- 

 ceeds precisely in the same manner as that in which 

 the new shoots of Pellia epiphyUa develope themselves, 

 with this difference only, that the transverse divisions of 

 the apical cells are always produced by means of septa 

 inclined to the horizon in alternate directions. The lateral 

 margins of the young shoots thus formed amalgamate 



