322 



MUSCINEM. 



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 transverse divisions then dividing again in a cruciform manner. 



Fig. 234.— First stage of development of the archego- 

 nium of Andreaea (after Kiihn) ; A terminal archegonium 

 arising from the apical cell of the shoot ; b b the youngest 

 leaves; 5 after the formation of the central cell and stig- 

 matic cell ; C transverse section of the young ventral 

 portion. 



FIG. 235. — Finiaria hyzrojnetrica ; A longitudinal section of the summit of a weak female plant (xioo), a archegonia, 

 b leaves ; B an archegonium (X550), b ventral portion with the central cell, h neck, w mouth still closed ; the cells of the 

 axial row are beginning to be converted into mucilage (the preparation was made after lying three days in glycerine) ; 

 C the part near the mouth of the neck of a fertilised archegonium, with dark red cell-walls. 



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 Archegonium 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. 235). 

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



