88 



MOSSES AND FERNS 



CHAP. 



which is not very largely developed, shows no definite arrange- 

 ment of the cells. The part of the wall of the capsule formed 

 from the four cover cells later become two-layered, but the rest 

 remains but one cell thick. In Metzgeria ^ the wall becomes 



later two - layered. The 

 A - archesporium divides first 



into two layers. In the 

 upper cells the divisions 

 are more regular than in 

 the lower one, and later 

 the archesporium is made 

 up of cells arranged in 

 more or less regular lines, 

 starting from just below 

 the apex and radiating 

 from this point, extending 

 to the base of the capsule. 

 These cells are at first of 

 similar form, and with the 

 growth of the capsule 

 become elongated with 

 pointed ends that fit to- 

 gether without any spaces 

 between. Some of these 

 cells, however, divide 

 rapidly by transverse walls 

 and give rise to rows of 

 isodiametric cells (Fig. "^,6, 

 sp), wedged in between 

 others that have remained 

 undivided (el). The former 



Fig. -iT.—Fossombronia longiscta (Aust.). A, Section are the yOUng SporOgCnOUS 

 through a young tetrad of spores; B, surface view ,, , Ipfff^r thp platpr<= 



of the wall of a young spore ; C, two young elaters, ^ciia, Liic idLLCi Liic ciducis. 



X 600 ; D, two ripe spores ; E,elater, X 300. ^ maSS of CClls lying jUSt 



below the apex, and be- 

 longing to the archesporium, remains but little changed, and 

 forms the point of attachment for the elaters after the capsule 

 opens (Fig. 36, B, C, 111). 



The further development of spores and elaters is similar to 

 that in the higher Marchantiaceae, and when the capsule is 



1 Leitgeb (7), vol. iii. PI. II. Fig. 9. 



