THE HIGHER CRTPTOGAMIA. 375 



the outer cells. In Selaglndla Galcottii the like divisions 

 are produced by longitudinal septa catting the free outer 

 surface of the cells in both parts of the cell of the third de- 

 gree adjoining the periphery of the terminal bud, i. e. in the 

 upper wedge-shaped five-surfaced moiety, as well as in the 

 lower which has six surfaces. Division by a horizontal 

 transverse septum however only takes place in the inner cell. 

 By this means the difference in the mode of cell-multiplica- 

 tion from that which occurs in Selac/inella Jiortensis is re- 

 moved (PL LVI, fig. 3).* 



When the end of the stem is about to become forked 

 there occur in addition to the divisions of the apical cell 

 by septa turned towards the narrow sides of the stem 

 divisions by septa inclined alternately towards the wide 

 sides of the stem. The top surface of the terminal cell 

 assumes, in consequence, the form of a parallelogram. The 

 divisions of the apical cell in the four different directions 

 follow one another in a left-handed spiral, as far at least as 

 observations go. This second form of the divisions of the 

 apical cell commences at a very early period in Selaginella 

 Jiortensis as early as the commencement of the formation 

 of the fourth pair of leaves of a segment of a shoot (PL LIV, 

 figs. 11, 12); in tSelaginella Galeottii and Martensi they 

 occur much later (PL LVI, fig. 4). In Selaginella Jiortensis 

 the forking of the stem commences at a very early period. 

 A transverse section through the end of the stem imme- 

 diately underneath the apex, exhibits four axile cells, in 

 which no one of the three directions of space preponderates. 

 These cells are surrounded by a simple wreath of twelve 

 cells somewhat stretched in a radial direction. Each two 

 of them form one of the small sides, each four of them one 

 of the wide sides of the terminal buds. The laterally com- 

 pressed form of the stem is visible close under the apex of 

 its growing end (PL LIV, fig. 7*). 



At first the portion of the axis above the youngest leaf 

 increases considerably in thickness. The number of the 



* My former notice of the succession of the divisions was (' Vergl. TJnters.' 

 p. 112), that the division of each of the halves into an inner and an outer cell 

 followed immediately after the first division of the cell of the second degree. 

 Repeated investigations have proved to me that the former division is preceded 

 by a division produced by an almost radial longitudinal septum. 



