86 MOSSES AND FERNS chap. 



the top of the antheridium, and next a pericHnal wall is formed 

 near the top of the central cells, by which a third peripheral 

 cell is formed in each half of the antheridium, which now con- 

 sists of two central cells and six peripheral ones. The further 

 divisions were not followed in detail, but seem to correspond 

 with those in the higher forms. 



Of the two first cells into which the dorsal cell divides, the 

 one which does not produce the antheridium, together with the 

 inner of the two into which that cell first divides, form a 

 partition which rapidly increases in height with the growth 

 of the antheridia, and separates each from its neighbour 

 by a single layer of cells, so that the antheridia are sunk 

 in chambers, arranged in two rows, corresponding to the two 

 series of segments of the apical cell. 



The archegonia are borne upon similar but shorter branches, 

 and here too the development is very regular. In Fig. 35, B, 

 a vertical section through the end of a young female branch is 

 shown with the apical cell (,f). Segments are here, too, cut off 

 alternately right and left, and from each segment an arche- 

 gonium develops. The segment is first divided, probably, as 

 in the male branch and the vegetative ones, into an inner and 

 an outer cell, but I did not succeed in getting satisfactory longi- 

 tudinal sections parallel to the surface, so cannot speak posi- 

 tively on this point. The youngest segment, in which the 

 archegonium mother cell is recognisable, shows in vertical sec- 

 tion three cells, a small ventral one, a middle larger one, and 

 a dorsal one — the archegonium mother cell. The latter does 

 not form any stalk, but divides at once by the three intersect- 

 ing walls, as in other Hepaticae, and the further development 

 corresponds with these, except that the base of the arche- 

 gonium is not free, and the central cell is below the level of 

 the superficial cells of the thallus. The archegonium neck is 

 short, and the basal part as well as that part of the venter 

 which is free, two cells thick (Fig. 35, C). The number of 

 neck cells is small (apparently about four), but whether the 

 number is constant cannot be stated positively. The female 

 branch remains very short, and the archegonia, which are only 

 produced in small numbers (usually not more than six to eight), are 

 close together and surrounded by an irregular sort of envelope 

 formed by the more or less incurved « and very much laciniated 

 margins of the branch. Secondary hair-like growths are also 



