112 



MOSSES AND FERNS 



CHAP. 



that the leaf, in whose axil the branch stands, has only the 

 dorsal lobe developed. In the other case, only a part of the 

 cell is devoted to forming the branch, and the rest forms a 

 diminished but evident ventral leaf-lobe, in whose axil the 

 young branch is situated. The formation of the intercalary 

 branches, which are for the most part of endogenous origin, 

 may be illustrated by Mastigobryiim, where the characteristic 

 flagellate branches arise in this manner. Here the apical cell 

 of the future branch (the branches in this case arise in strictly 

 acropetal order) springs from the ventral segment, and exactly 

 in the middle. It is distinguished by its large size, and is 

 covered by a single layer of cells (Fig. 53). In this cell the 

 first divisions establish the apical cell, which then grows in the 



usual way. The young 



am. 



Fig. 54. — Ventral surface of the stem of Chiloscyphus c^,,. 



bmatus (N. von E.), showing amphigastria {am), X 14 (after tnrOUgh it, 

 Schiffner). 



bud early separates at 

 the apex from the 

 overlying cells, which 

 rapidly grow, and form 

 a dome-shaped sheath, 

 between which and the 

 bud there is a space of 

 some size. Later the 

 young branch grows 

 more rapidly than the 

 sheath and breaks 



The 



no n -sexual 



reproduction of the acrogynous Hepaticse may be brought 

 about either by the separation of ordinary branches through 

 the dying away of the older parts of the stem, or in a 

 few cases observed ^ new plants may arise directly from 

 almost any point of a leaf or stem. Gemmae are known in a 

 large number of species. These in most of the better 

 known cases are very simple unicellular or bicellular buds 

 arising often in great numbers, especially from the margins 

 and apices of leaves. Curious discoid multicellular gemmae 

 have been discovered in a number of species, especially 

 in several tropical ones investigated by Goebel.^ The gemmae 

 upon the thallus of Lejeunia inetzgeriopsis are of this character, 

 and similar ones are found in Colokjeunia Goebelii. In the 

 1 Schiffner (i), p. 67. 2 Goebel (15). 



