372 . MUSCINEX. 



arises in exactly the place in which a branch would otherwise be formed, 

 /'. e, from the segment of the axis which lies beneath the cathodal half of the 

 leaf; the antheridia may in this case be considered as metamorphosed branches. 

 In Foniinalis, on the other hand, their morphological significance varies within 

 the same receptacle; the one first formed is the immediate prolongation of 

 the axis of the shoot, arising from its apical cell; the succeeding ones are 

 developed from its last normal segments, and therefore resemble leaves in 

 their origin and position ; the last antheridia, finally, exhibit the morphological 

 characters of trichomes, both in their variable number, their development as cells 

 of the epidermis, and the want of definiteness in their place of origin. According 

 to Kiihn, AndrecEa behaves in precisely the same way as Fontinalis. The mother-cell 

 of the antheridium of Fontinalis is constituted as an apical cell forming two 

 alternating rows of segments; in forming the oldest and terminal antheridium 

 the apical cell changes from a triseriate to a biseriate segmentation. These seg- 

 ments are next divided by tangential walls in such a manner that the transverse 

 section (which meets two segments) of the young organ shows four outer and 

 two inner cells; the wall of the antheridium, one cell in thickness, arises from 

 the former by further division; the small-celled tissue which produces the anther- 

 ozoids from the latter. Andrecea behaves also very similarly in these respects; the 

 primary mother-cell of the antheridium appears as a papilla and is cut off by a 

 septum; the lower cell produces a cushion-like support; the upper cell is again 

 divided by a septum into a lower cell from the divisions of which the tissue of 

 the stalk is formed, and an upper cell out of which the body of the antheridium 

 arises ; the formation of the latter takes place in the same manner as in Fontinalis. 

 In Sphagnum the long stalk originates by transverse divisions of the growing 

 papilla which produces the antheridium, the segments dividing again in a cruciform 

 manner. The terminal cell then swells, and becomes divided by oblique walls of 

 somewhat irregular position ; a tissue is thus formed, which, at a subsequent period, 

 consists also of a wall formed of a single layer of cells and an inner very small-celled 

 tissue which produces the antherozoids. 



The Archegoniu?n consists when mature of a massive, moderately long base, 

 which supports a roundish ovoid ventral portion ; above this rises a long thin neck, 

 generally twisted on its axis. The wall of the ventral portion, which consists, even 

 before fertilisation, of a double layer of cells, passes up continuously into the wall of 

 the neck consisting of a single layer of cells formed of from 4 to 6 rows (Fig. 256). 

 Together they enclose an axial row of cells, the lowest of which, ovoid and lying 

 in the ventral portion, produces the oosphere and the ventral canal-cell, the upper 

 cells being the canal-cells of the neck. These and the ventral canal-cell become 

 mucilaginous before fertilisation. This mucilage forces the four uppermost cells 

 (stigmatic cells) of the neck apart, and thus opens the canal of the neck, allowing 

 the antherozoids to penetrate to the oosphere. Fig. 256, B^ shows the row of 

 canal- cells at the period when disorganisation is beginning, and when the stigmatic 

 cells of the neck are still closed. In reference to the morphological significance 

 of the archegonia, Leitgeb has already shown that at least the first archegonium 

 of Sphag?ium arises immediately from the apical cell of the female shoot; more 

 recently Kiihn found that in Andrecea the first is formed from the apical cell, the 



