122 



STRUCTURAL BOTANY 



developing spores. At a later stage they play a part in 

 the dissemination of the spores, as we shall see further 

 on. In Pellia the elaters radiate from the base of the 

 capsule, where they are attached to a mass of shorter 

 cells, likewise spirally thickened. They extend from 



this part, upwards and 

 outwards, passing between 

 the mother-cells, which 

 chiefly occupy the outer 

 and upper part of the 

 capsule (Fig. 55). Young 

 elaters, with the spiral 

 bands just beginning to 

 form, are shown in Fig. 

 56, and nearly mature 

 ones are represented in 

 Fig. 57 among the spores. 

 The mother-cells of the 

 spores, which are very 

 numerous, are of a peculiar 

 shape. At an early stage 

 they become very deeply 

 FIG. 55 -Young fruit of Pellia, in f our _i bed, the lobes being 



longitudinal section. It is enclosed 



within the calyptra. n, neck of tetrahedrally arranged, so 



fied40 Me (R. ; sf) f 



that only three are seen 

 /, foot of sporogonium ; sp, spore in one plane (Fig. 56, sp). 



The lobes are connected 

 in the middle by a quite 

 narrow neck, in which the nucleus, which remains for 

 a long time undivided, is situated. Eventually the 

 nucleus of the mother - cell divides into four, each 

 daughter-nucleus travelling out into one of the lobes, 

 which now become separated from one another by celj- 



