96 



MOSSES AND FERNS 



CHAP. 



the growth of the capsule become elongated with pointed 

 ends that fit together without any spaces between. Some 

 of these cells, however, divide rapidly by transverse walls 

 and give rise to rows of isodiametric cells (Fig. 45, sp), 

 wedged in between others that have remained undivided (el). 



The former are the young 

 A . sporogenous cells, the 



latter the elaters. A mass 

 of cells lying just below 

 the apex,- and belonging 

 to the archesporium, re- 

 mains but little changed, 

 and forms the point of 

 attachment for the elaters 

 after the capsule opens 

 (Fig. 45, B, C, m). See 

 also Goebel ((21), pp. 



325-327- 



The further develop- 

 ment of spores and ela- 

 ters is similar to that in 

 the higher Marchantia- 

 cese, and when the cap- 

 sule is mature it opens by 

 four valves which extend 

 its whole length. 



The first division-wall 

 in the embryo of Fos- 

 sombronia longiseta is 

 transverse and divides it 

 into two somewhat un- 

 equal cells, of which the 

 lower and smaller one 

 gives rise to the foot, and 

 not merely to the append- 

 age of the foot, as is the 

 case in Anciira. From the upper cell arise the seta and the 

 capsule. A second transverse wall (Fig. 47, 11.) is formed 

 before any longitudinal walls appear. The upper of the three 

 cells gives rise, not only to the capsule, but to part of the seta 

 as well. The separation of the primary archesporial cells is 



Fig. 46. — Fossombronia longiseta. A, Section 

 through a young tetrad of spores; B, surface 

 view of the wall of a young spore; C, two 

 young elaters, X6oo; D, two ripe spores; E, 

 elaters, X300. 



