CHAPTER VII 



THE BRYINE^ 



Under the name Bryineae may be included all the other 

 Mosses ; for although the so-called cleistocarpous forms are 

 sometimes separated from the stegocarpous Mosses as a special 

 order, the Phascaceae, the exact correspondence in the develop- 

 ment of both the gametophyte and sporophyte shows that the 

 two groups are most closely allied, the former being either 

 rudimentary or degraded forms of the others. 



With few exceptions the protonema is filamentous and 

 shows branches of two kinds, the ordinary green ones with 

 straight transverse septa, and the brown-walled rhizoids with 

 strongly oblique ones, but the two forms merge insensibly into 

 one another, and are mutually convertible. In a few forms, 

 notably the genus Tetraphis, the protonema is thalloid, and as 

 in Sphagnum these flat thalli give rise to filamentous protonemal 

 threads, which in turn may produce secondary thalloid proto- 

 nemata. In some of the simpler forms, e.g. Epheinerum, the 

 protonema is permanent, and the leafy buds appear as append- 

 ages of it ; but in most of the larger Mosses the primary 

 protonema only lives long enough to produce the first leafy 

 axes, which later give rise to others by branching, or else by 

 secondary protonemal filaments growing from the basal rhizoids.. 

 The early stages of development of the primary protonema are 

 easily traced, as the spores of most Mosses germinate readily 

 when placed upon a moist substratum. The ripe spores usually 

 contain abundant chlorophyll and oil, and the thin exospore is 

 brown in colour. The spore absorbs water and begins to 

 enlarge until the exospore is burst, when the endospore pro- 

 trudes as a papilla which grows out into a filament ; or the 



