153 



SECOND GROUP. MUSCINEAE. 



and the stalk proceed from the upper cell, while the lower cell appears as an 

 appendage or foot (Fig. 101, a) at the end of the stalk, though in many cases it under- 

 goes some further divisions. A somewhat older embryo shows in its upper portion a 

 cellulose skeleton formed of a number of transverse tiers, which consist each of four 

 cells in the form of quadrants of a cylinder, while the apex is occupied by four cells 

 in the form of octants of a sphere. It is from these latter that the capsule proceeds 

 in the simpler cases, such as Pellia, Frullama, Lejeum'a, a wall-layer being separated 

 off by four periclinal walls from four inner cells, the archesporium (Fig. 101, C). 

 But in most cases the tier of cells adjoining the four upper cells also takes part in the 

 formation of the capsule. The part beneath the capsule, in which the separate tiers 



FIG lot. Development of the embryo of the Liverworts more or less diagranimatically represented. The cells from 

 which the sporogenous tissue is formed are shaded. A Riccia, in which all the cells except those of the parietal layer are 

 devoted to the production of spores. B Marchantia ; the oosphere is divided by the first wall, formed in it after fertilis- 

 ation, into a lower portion which becomes the stalk and an upper which forms the capsule fCa, C Pellia epiphylla; 

 a appendage of the embryo, the archesporium is composed of four cells, of which two are visible. D Anthoceros ; the 

 archesporium is a bell-shaped cell-layer; col the columella. E Jungermannia biCHSpidata. F Raditla complanafa', 

 the archesporium consists of more than four cells. The bracket in Fig. C indicates the portion of the embryo from which 

 the stalk of the sporogonium proceeds. After Kienitz-Gerloffand Leitgeb. 



are still visible, becomes the stalk, and its basal portion often swells up into a thickened 

 foot. The spore-chamber as it grows becomes round, and the stalk elongates very 

 considerably when the capsule is mature, and lifts it into the air. The development 

 of the embryo in Anthoceros is most unlike that of the other genera; its first stages 

 are the same as in the Jungermannieae ; the embryo consists of two to three tiers of cells 

 disposed as quadrants. In this case there is no stalk, but a foot proceeds from the 

 lowest tier, and the capsule from the two upper, or from the one upper tier. The cells 

 of this tier are divided by periclinal walls into inner and outer cells. But while in the 

 rest of the Hepaticae the outer cells form the wall and the inner the archesporium, it 



