176 MOSSES AND FERNS chap. 



Mosses, and will be passed over for the present. The ripe 

 archegonium shows no noteworthy peculiarities, and closely 

 resembles in all respects that of the other Mosses. 



The Sporogonium 



The more recent researches of Waldner ^ on the develop- 

 ment of the sporogonium of AndrecEu have shown clearly that 

 here, too, the latter stands between the Sphagnaceae and the 

 Bryineae. The first division in the fertilised ovum is transverse 

 and divides it into two nearly equal parts. The lower of these 

 divides irregularly and much more slowly than the upper one. 

 In the latter (Fig. 83, E) the first division wall is inclined, and 

 is followed by a second one which meets it nearly at right 

 angles, and by walls inclined alternately right and left — in 

 short, has the character of the familiar " two-sided " apical cell. 

 The number of segments thus formed ranges from eleven to 

 thirteen. Each segment is first divided by a vertical median 

 wall into equal parts, so that a cross -section of the young 

 embryo at this stage shows four equal quadrant cells. The 

 next divisions correspond to those in Sphagnum, and result in 

 the separation of the endothecium and amphithecium. The 

 formation of the archesporium, however, differs from Sphagnwn, 

 and is entirely similar to that of the higher Mosses. Instead 

 of arising from the amphithecium as in the former, the arche- 

 sporium here is formed by the separation of a single layer of 

 cells from the outside of the endothecium. All of the segments 

 do not form spores, but only three or four, beginning with the 

 third from the base. The two primary segments of the upper 

 part of the embryo, like the corresponding ones in Sphagnum, 

 go to form the foot, which is not so well developed, however, 

 as in the latter. The originally one-layered archesporium later 

 becomes double, and as in Sphagnum extends completely over 

 the columella, which is thus not continuous with the tissue of 

 the upper part of the sporogonium. As in Sphagnum also, no 

 trace of the intercellular space formed in the amphithecium of 

 the Bryineae can be detected. A section of the nearly ripe 

 capsule shows the club-shaped columella extending nearly to 

 the top of the cavity. With the growth of the capsule the 



1 Waldner (2). 



