I02 MOSSES AND FERNS .chap. 



the archegonial branches are much less conspicuous than the 

 antheridial ones. The older ones, which either contain a young 

 sporogonium or abortive archegonia, are readily distinguished 

 on account of the large perianth (Fig. 41, A), but those that 

 contain the young archegonia are situated very near the apex 

 of the main shoot, and are scarcely to be distinguished from 

 the very young vegetative branches. However, a plant with 

 the older perichajtia, or very young sporogonia, will usually 

 show young archegonial branches as well. 



The archegonial branch originates in the same way as the 

 vegetative branches, and the first divisions of its apical cell are 

 the same ; but only two or three segments develop leaves, 

 after which each young segment divides into an inner and 

 an outer cell ; the latter becomes at once the mother cell of 

 the young archegonium. The inner cell divides further by a 

 transverse wall, and the outer of the two cells thus formed gives 

 rise to the short but evident pedicel of the archegonium. The 

 latter is very like that of the anacrogynous Liverworts. Of the 

 three first walls (Fig. 46, C), the last formed one is much 

 shorter, so that one of the three peripheral cells is much 

 smaller, and does not divide by a vertical wall, and the neck 

 has but five rows of cells, as in Pellia. This appears to be 

 universal among the Jungermanniaceae examined.^ Often in 

 Porella the three primary walls converge at the bottom so as 

 to almost meet, in which case the central row of cells is 

 narrower at the base (Fig. 46, D). The rest of the develop- 

 ment is exactly as in the other Hepatic^. The number of 

 neck canal cells in the full-grown archegonium is normally 

 eight. The archegonium (Fig. 46, L) at maturity is nearly 

 cylindrical, with the venter but little enlarged. The canal cells 

 are broad, but the egg small. The venter has a two-layered wall. 



The first -formed archegonia arise in strictly acropetal 

 succession, and finally the apical cell divides by a transverse 

 wall, and the outer cell so formed becomes transformed into an 

 archegonium. In a number of cases observed, young arche- 

 gonia were noticed among the older ones, apparently formed 

 secondarily from superficial cells between them, and not from 

 the younger segments of the apical cells. 



A perianth is formed about the group of archegonia, much 

 as in the anacrogynous forms. 



^ Janczewski (i), p. 393. 



