i8o 



MOSSES AND FERNS 



CHAP. 



The ripe capsule opens by a circular lid which is indicated 

 long before it is mature. The epidermal cells where the open- 

 ing is to occur grow less actively than their neighbours, and 

 thus a groove is formed which is the first indication of the oper- 

 culum. The cells at the bottom of the groove have thinner 



walls than the other cells 

 of the capsule wall, and 

 when it ripens these dry 

 up and are very readily 

 broken, so that the oper- 

 culum is very easily sep- 

 arated from the dry cap- 

 sule. Stomata, according 

 to Schimper, always are 

 present, sometimes in 

 great numbers; but Hab- 

 erlandt ((4), p. 475 )> 

 states that these are al- 

 ways rudimentary, and 

 he regards them as re- 

 duced forms. No seta is 

 formed, but its place is 

 taken physiologically by 

 the upper part of the axis 

 of the archegonial branch, 

 which grows up beyond 

 the perichaetium, carrying 



FIG. 93- Median longitudinal section of a tllC ripe SpOrOgOnilllll at 



nearly ripe sporogonium of S. acutifoli- jj-g ^Qp (pjo\ nj E). The 

 um, X24; ps, pseudopodium ; sp, spores; ' . 



col, columella (after Waldner). Upper part Of thlS pSCU- 



dopodium" is much en- 

 larged, and a section through it shows the bulbous foot of the 

 capsule occupying nearly the whole space inside it. The ripe 

 capsule breaks through the overlying calyptra, the upper part 

 of which is carried up somewhat as in the higher Mosses, while 

 the basal part together with the upper part of the pseudopodium 

 forms the "vaginula." 



The disorganised contents of the canal cells, which are 

 usually ejected from the archegonium, in Sphagnum remain in 

 a large measure in the central cavity, and on removing the 



