THE HIGHER CRYPTOGAMIA. 95 



(according to Bischoff) the contents of the antheridiura 

 escape in the form of mucilaginous drops. 



In the apical cell of the rudiment of an archegonium 

 division takes place in often-repeated succession by alter- 

 nately inclined septa. Here, also, the cells of the second 

 degree divide immediately after their formation by radial 

 septa. Immediately after the formation of the radial 

 septum which divides the cell of the second degree, septa 

 parallel to the axis 'appear in one of the four longitudinal 

 rows of cells of the third degree ; these latter septa divide 

 the mother-cells into inner three-sided and outer four- 

 sided cells, so that the organ now consists of a central 

 string of cells, which is surrounded by a single layer of 

 cells arranged in sets of four cells of equal height (PI. 

 XIII, figs. 12, 13). The apex of the young archegonium 

 swells to a clavate shape ; contemporaneously, the basal 

 cell of the central row of cells begins to enlarge its circum- 

 ference, whereby the base of the archegonium becomes 

 distended (PL XIII, fig. 13). The cellular tissue sur- 

 rounding the archegonia, so far from amalgamating with 

 their outer cellular layer, is often, on the contrary, ex- 

 panded into a wide cavity surrounding the base of the 

 archegonium (PI. XIII, fig. 15). The cells of the stem, 

 on the other hand, usually become very closely approximated 

 to the neck of the archegonium, without, however, be- 

 coming actually united to it. In comparison with other 

 mosses, the basal cell of the central string of cells becomes 

 considerably enlarged; this takes place, however, at a 

 somewhat later period, shortly before the rupture of the 

 apex of the archegonium. Within the fluid contents of 

 this basal cell there is produced a free spherical cell 

 (PL XIII, figs. 14, 15). This grows by degrees, until it 

 fills the mother-cell. There are but few of the Muscales 

 in which this cell is so clearly distinguishable as in Riccia. 

 The remaining cells of the central string are dissolved, 

 and the apex of the archegonium opens. The archegonia, 

 thereupon, either wither, which is a rare occurrence, or a 

 fruit is formed in their ventral portion. The first indica- 

 tion of fruit-formation is the division, by means of an in- 

 clined septum, of the free cell which has originated in the 



