122 



STRUCTURAL BOTANY 



ctr. 



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 ou r-lobed, the lobes being 



longitudinal section. It is enclosed ' 



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



archegonium, in which the fruit was fi *. i fhrpp flr p 

 formed ; ar, abortive archegonia ; 



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



mother-cells ; el, elaters. Magni- mi i i 



fied 40. (R. S.) ^ ne lbes 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 cell- 



