io6 



MOSSES AND FERNS 



CHAP. 



moderate size, and rich in chromatin, has a distinct nucleolus. 

 The elaters have thinner walls than the spore mother cells, and 

 the contents are more finely granular. A distinct nucleus 

 staining strongly with the usual reagents is present. The 

 further history of spores and elaters corresponds closely with 



that of the forms already described. 

 The ripe spores have only a thin 

 wall, which is coloured brown, and 

 has delicate granular thickenings. 



In a paper by Le Clerc du 

 Sablon ^ the statement is made, and 

 figures are given, showing that at an 

 early stage in the development of 

 the spores and elaters of a number 

 of Hepaticae the walls of the cells 

 are completely destroyed, so that 

 the young spore mother cells and 

 elaters are primordial cells. A 

 great many carefully stained micro- 

 tome sections of a large number of 

 Liverworts belonging to all the 

 principal groups have been examined 

 by me, and invariably the presence 

 of a definite cell wall can be demon- 

 strated at all stages. 



Many of the foHose Hepaticae 

 show much greater regularity in the 

 early divisions of the embryo, and 

 in the establishment of the arche- 

 sporium and the arrangement of its 

 cells. This is especially marked in 

 Fnillania? Here, after the upper 

 Fig 49.-M« Boianderi (Aust.). ^ ^ embryo has divided into 



Longitudinal section of a sporo- i:"-^'- <- ^'- ^'^'■^ ^^l^ij^ j ^ 



gonium after the final division of the thrCC tlcrS of Cclls, thcSe UudcrgO 



sporogenous cells, X 85. , , , , . . . , 



the usual quadrant divisions, and 

 the four terminal cells only, form 

 the capsule, in which the archesporium is established by 

 the first periclinal walls (Fig. 50). The divisions in the 

 archesporium are also extremely regular, so that the spores 

 and elaters form regularly alternating vertical rows. In 

 1 Le Clerc du Sablon (3). - Leitgeb (2), vol. ii. 



