VI MOSSES (Af use/) : SPHAGNACE./i—ANDRE.EACE.'E 175 



sivelv. Where there are crevaces in the rock, some of these 

 branches grow into them as colourless rhizoids, but here, as in 

 the Bryineai, there is no real morphological distinction between 

 rhizoid and protonema. Most of the filamentous protonemal 

 branches do not remain in this condition, but become trans- 

 formed into cell plates or cylindrical cell masses, like the stem- 

 rhizoids. The flat protonema recalls strongly that of Sphagnum, 

 and is probably genetically connected with it. All of the 

 different protonemal forms, except what Kiihn calls the " leaf- 

 like structures," vertical cell surfaces of definite form, can give 

 rise to the leafy axes. The development of these seems to 

 correspond exactly with that of the other Mosses, and will not 

 be further considered here. 



The Sexual Organs 



The species of Andrecea may be either monoecious or 

 dioecious. Archegonia and antheridia occur on separate 

 branches, but their origin and arrangement are identical. The 

 first-formed antheridium develops directly from the apical cell 

 of the shoot, and the next older ones from its last-formed 

 segments, but beyond this no regularity can be made out. In 

 the first one the apical cell projects, and its outer part is 

 separted from the pointed inner part by a transverse wall. 

 This is followed by a second wall parallel to the first, so that 

 the antheridium rudiment is composed of three cells. Of these 

 the lower one takes little part in the future development. Of 

 the two upper cells the terminal one becomes the body of the 

 antheridium, the other the stalk. In the former, by two inclined 

 walls, a two-sided apical cell is developed, and the subsequent 

 growth is the same as in the Bryineae. The middle cell of the 

 antheridium rudiment divides repeatedly by alternating trans- 

 verse and longitudinal walls, and forms the long two-rowed 

 stalk of the mature antheridium. On comparing the antheridium 

 with that of the other Mosses, we find that it approaches 

 Sphagnum in the long stalk, but in its origin and the growth 

 of the antheridium itself, it resembles closely the higher Mosses. 



The first archegonium also is derived immediately from the 

 apical cell of the female branch, and the first divisions are the 

 same as in the first antheridium. Here, too, the subsequent 

 development corresponds exactly with that of the higher 



