MOSSES, 



321 



from the foliage-leaves ; they are broader and shorter, expanded horizontally at the 

 upper part, delicate and of a pale green, orange, or purple colour ; they are always 

 smaller the nearer the leaf-spiral approaches the centre; the antheridia stand in 

 their axils (]Mnium, Polytrichum, Pogonatum, Dawsonia). The paraphyses stand 

 between or by the side of the sexual organs ; in the female flowers they are always 

 articulated filaments ; in the male flowers filiform or spathulate, and consisting, in 

 the upper part, of several rows of cells. 



T/ie Antheridia are, when mature, stalked sacs with a wall consisting of a sino-le 

 layer of cells containing grains of chlorophyll, which however, in the ripe state, 

 assume a red or yellow colour. In the Sphagnacece and in Buxbaumia the antheridia 

 are nearly spherical, but in all other ^Mosses of an 

 elongated club shape. In the Sphagnacece they 

 open in the same manner as in the Hepaticae ; 

 in the other orders by a slit across the apex, 



through which the antherozoids still enclosed • ,;, 



in their mother-cells are discharged as a thick 

 mucilaginous jelly. The interstitial mucilage dis- 

 solves in water, and the antherozoids escape from 

 their mother-cells and swim about free. 



The careful investigations of Leitgeb show 

 that the morphological significance of the an- 

 theridia is very various. In Sphagnum the 

 mother-cell of the andieridium arises in exactly 

 the same place in which a shoot would otherwise 

 be formed, i.e. from the segment of the axis of the 

 antheridial shoot which lies beneath the cathodal 

 half of the leaf; the antheridia may in this case 

 be considered as metamorphosed shoots. In 

 Fontinalis, on the other hand, their morpholo- 

 gical significance varies within the same flower ; 

 the one first formed is the immediate prolonga- 

 tion 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, Andresea 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 seg- 

 ments ; in forming the oldest and terminal antheridium the apical cell changes 

 from a triseriate to a biseriate segmentation. These segments 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 antherozoids from the latter. 



Y 



Fig. 233. — Fnnaria hygrometyfca ; A an anthe- 

 ridium bursting, a the antherozoids (X3S0) ; R the 

 antherozoids more strongly magnified, b in the 

 mother-cell ; c free antherozoid of Polytrichum 

 {X800). 



