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BKArrmvAiTE : liiE study of mosses. 



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spore-sac, and in ilie centre the columellaj to which the spore-sac 

 is generally closely applied. 



If we take a capsule when the calyptra is just cast off; we 

 see that the upper end is closed by a lid or operculum, flat, 

 conical, or with a long beak, by the falling away of which, exit 



is given to the spores, but in a few ill-developed mosses, we find 

 no line of dehiscence for the separation of a lid, and hence 



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these were formerly grouped togetlier as cleistocarpous or closed- 

 fruited mosses, and the spores only escaped when the capsule 

 rotted. Now these lowly specimens are referred to the families 

 with which they agree in habit and leaf structure, and we look 

 upon them as imperfectly developed mosses. 



Between the capsule mouth and the lid is usually an 

 annulus or ring of several rows of vesicular cells, which swelling 

 by moisture, act as wedges, and lift up the lid, by the removal 

 of which the peristome coa:ies into view, a series of jointed teeth 

 guarding the capsule-mouth, which are always multiples of 4, 

 being 4, 8, 16, 32, or 64. 



The species with four teeth arc represented here by two 



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species of Georgia^ and the teeth consist of four pyramidal 

 masses of cells composing the Internal tissue of the lid. Another 

 considerable family, the Polytrichace^, have sixteen, thirty-two, 

 or sixty-four peculiar teeth formed of bundles of fine threads 

 united by cellular tissue into flat plates, the point of the teeth 

 being bound down to the circular dilated top of the columella 

 which closes the mouth, and is termed the epiphragm or tym- 

 panum. In most other mosses the teeth, when most highly 

 developed, are formed of thickened plates in two strata, the 



