374 HOFMEISTER, ON 



division in the apical cell, the second youngest cell of the 

 stem which adjoins the apical cell divides into two halves 

 by a longitudinal septum cutting the narrow side of the 

 terminal bud, and inclined towards one of the wide sides of 

 the end of the stem (PL LVI, figs. I s , ]/). Each of the two 

 halves is divided by a longitudinal septum which is concave 

 towards the septum last formed, and cuts the boundary wall 

 of the adjoining cell, which latter cell was produced by the 

 multiplication of the next younger cell of the second degree. 

 Of the two cells into which each half is thus divided one is 

 turned towards the narrow, and the other towards the wide 

 side of the stem. The former is a four- sided prism, the 

 latter a three-sided one with curved lateral surfaces. The 

 four-sided daughter-cell then divides, by a septum parallel 

 to the longitudinal axis of the stem, into an inner and an 

 outer cell. Frequently in Selaginella Galeottii, less often in 

 other species, this latter cell-duplication is preceded by the 

 production of a septum which cuts the upper and the free 

 outer wall of the cell of the third degree at a very acute 

 angle (PI. LVI, fig. 3). This mode of cell-multiplication 

 differs from what takes place in Selaginella denticulate, 

 helvetica, viticulosa, Martensi, and others, where the more 

 ordinary cell-succession occurs, and the result of the differ- 

 ence is, that a half-girdle of wedge-shaped cells is interpo- 

 lated between each two of the groups of cells produced by 

 the multiplication of a cell of the second degree. In this 

 case the division into an inner and an outer cell by a septum 

 parallel to the axis of the stem, takes place only in the larger, 

 lower half of the four-sided cell of the third degree. 



The three-sided cell of the third degree of the stem of 

 Selaginella hortensis, helvetica, &c. is divided into two un- 

 equal parts by the formation of a longitudinal septum 

 which is attached in a radial direction to the free outer 

 surface of the cell, verv near to the original side-wall of the 

 cell of the second degree. The cells produced by the mul- 

 tiplication of the cell of the second degree are now all 

 divided transversely by membranes which are parallel to the 

 former boundary wall between the cell of the second degree 

 and the apical cell (PI. LIV, figs. 8, 9). This latter divi- 

 sion usually occurs somewhat later in the inner cells than in 



