MOSSES. 153 



Upon the capsule is a peculiar cap, shaped like a ladle or 

 spatula, the calyptra. 



252. Structure of the moss capsule. — At the free end on 

 the moss capsule as shown in the case of mnium in fig. 128, 

 after the remnant of the archegonium falls away, there is seen 

 a conical lid which fits closely over the end. When the capsule 

 is ripe this lid easily falls away, and can be brushed off, so that 

 it is necessary to handle the plants with care if is desired to 

 preserve this for study. 



253. Opening of the capsule. — When the lid is brushed away 

 as the capsule dries more, we see that the end of the capsule 

 covered by the lid appears " frazzled. " If we examine this end 

 with the microscope we will see that the tissue of the capsule 

 here is torn with great regularity, so that there are two rows of 

 narrow, sharp teeth which project outward in a ring around the 

 opening. If we blow our " breath " upon these teeth they will 

 be seen to move, and as the moisture disappears and reappears 

 in the teeth, they close and open the mouth of the capsule, so 

 sensitive are they to the changes in the humidity of the air. 

 In this way all of the spores are prevented to some extent from 

 escaping from the capsule at one time. 



254. The male and female moss plants. — The two plants 

 of mnium, shown in figs. 129, 130, are quite different, as one 

 can easily see, and yet they belong to the same species. One 

 is a female plant, while the other is a male plant. The sexual 

 organs, then, in mnium, as in many others of the mosses, are 

 borne on separate plants. The archegonia are borne at the 

 end of the stem, and are protected by somewhat narrower 

 leaves which closely overlap and are wrapped together. They 

 are similar to the archegonia of the liverworts. 



The male plants of mnium are easily selected, since the 

 leaves at the end of the stem form a broad rosette with the 

 antheridia, and some sterile threads packed closely together in 

 the centre. The ends of the mass of antheridia can be seen 

 with the naked eye, as shown in fig. 130. 



