58 



which border its mouth. This fringe is called the peristome 

 (Fig. 5). When the spores are mature, the annulus by its con- 

 tractions forces off the operculum and calyptra. The dispersal 

 of the spores is brought about by the opening and closing of the 

 peristome which acts as a sifter for the spores. The peristome 

 is very hygroscopic and thus serves to control spore dispersal 

 according as the conditions are favorable or unfavorable (Fig. 2). 



The spores are carried by the wind and if a favorable substra- 

 tum be found, the spore will germinate. The germination of 

 the spore consists in the rupture of its wall followed by the pro- 

 trusion of the germ tube (Fig. i, A, B). This soon produces 

 branching algal-like filaments known as the protonema. The 

 protonema produces rhizoids, these absorb nourishment from the 

 substratum. Buds soon appear on the branches. These buds 

 grow out to be the leafy stem or gametophyte of the moss plant 

 (Fig. I, C, D). 



Sex organs are developed on the ends of stems or branches. 

 The male branches are called the antheridial branches (Fig. 4). 

 The female branches are called the archegonial. Plants are either 

 monoecious or dioecious according as antheridia or archegonia are 

 found on one or separate plants. Antheridia are usually carried 

 to the archegonia by a drop of water. After fertilization, the 

 growth of the sporophyte generation commences. The germina- 

 ation of the gametospore or fertilized egg results in the develop- 

 ment of seta and capsule with its contained spores and also the 

 protecting modifications, the peristome, operculum and calyptra 

 (Fig. 2). 



In order to ascertain the name of a particular moss, several 

 features must be noted. 



First of all, the place of origin of the seta on the stem. This is 

 of importance, for it enables one to see at a glance the two great 

 divisions into which all mosses are divided. If the seta originates 

 at the apex of the leafy stem, then all forms having this arrange- 

 ment are grouped together under the division known as the 

 acrocarpous forms. If, on the other hand, the seta arise from a 

 lateral branch, then mosses of this kind are included in the 

 division called the pleurocarpous. 



