Muscr. 



^75 





of cells; the cells contain chlorophyll,' but when mature they are coloured yellow or 

 red. In the S})hagnaceae and Buxbaumia the antheridia are nearly spherical, in all 

 other Mosses elongated club'shaped. In the Sphagnaceae they open in the same 

 way as in the Hepaticae; in the other subdivisions by a tissue at the apex, through 

 which the spermatozoids issue forth in their cysts as a thick mucilage ; they are at 

 first still imbedded in a mucilage, but this dissolves in the water and the spermatozoids 

 slip out of their cysts and swim away. 



According to Leitgeb's researches the point of origin of the antheridium is not in 

 all cases the same ; in Sphagnum the mother-cell of the antheridium originates exactly 

 at the spot where a shoot is usually formed, that is, from the segment, of the axis of 

 the antheridial shoot below the kathodic half of the leaf. In Fontinalis and indeed 

 in most other Mosses the point of origin varies within the 

 same group of sexual organs ; the first antheridium is the 

 direct prolongation of the axis of the shoot and arises from 

 its apical cell ; those that follow it are developed from its 

 last normal segments, and agree with the leaves in respect 

 to their origin and position ; those formed last come from 

 superficial cells, and are not confined to any definite jioin'. 

 The mother-cell of the antheridium of Fontinalis is like an 

 apical cell which forms two alternating rows of segments ; 

 in the case of the oldest and terminal antheridium therefore 

 the apical cell of the shoot ceases to form three rows of seg- 

 ments and now only forms two, a proceeding mentioned 

 above as occurring in the shoots of Fissidens, and which will 

 be described below in connection with the apical cell of the 

 stem of the embryo of Salvinia natans. The segments are 

 first divided by anticlinal and periclinal walls in such a 

 manner that the transverse section, which includes two seg- 

 ments, shows four outer and two inner cells ; the former by 

 further division gives rise to the one layered wall; the latter 

 to the small-celled tissue which produces the spermatozoids. 

 The mode of proceeding is similar in Andreaea, where the 

 primary mother-cell of the antheridium makes its appearance 

 as a papilla which is cut off by a transverse wall ; the lower 

 cell produces a cushion-like foot; the upper is divided ^oo times. 

 once more by a transverse wall into a lower cell from which proceeds the tissue of 

 the stalk, and an upper which gives rise to the body of the antheridium ; the mode of 

 formation is in fact the same as in Fontinalis. In Sphagnian the long stalk is formed 

 by transverse divisions of the growing papilla which is the rudiment of the antheridium ; 

 then the segments divide cross-wise, and the terminal cell swells out and is divided 

 by oblique walls of somewhat irregular position ; in this way a mass of cellular tissue 

 is formed, which subsequently consists of a wall of one layer of cells and an inner 

 very small-celled tissue which produces the spermatozoids. 



The archegonium when fully formed consists of a thick and rather long stalk, 

 a roundish-ovoid venter resting on the stalk, and above it a long slender neck usually 

 twisted on its axis. The wall of the venter, which is formed of two layers of cells 



VIC 128. Fituayta /tyj^romf- 

 tn'ca, ./antheridium opening; a 

 the spermatozoids. B a spennato- 

 zoid more highly magnified ; b in 

 the cyst, c a free spermatozoid of 

 Polytrichutn. A magn. 350 times, 

 B more higlily magnified, c magn. 



