LYCOPODIACK^ — MUSCI OK BEYACEjE. 641 



growths. — They are moss-like plants, intermediate between ferns and 

 mosses, and in some respects allied to cone-bearing plants. They 

 abound in warm, moist, insular climates. A species of Selaginella 

 from Jamaica has a green hue during the day, and turns white to 

 the eye at night. There are 6 genera and about 200 species. 

 Examples — Lycopodium, Selaginella, Isoetes. 



Some of the Lycopodiums are emetic and cathartic. The powdery 

 matter in the thecse is inflammable, and has been used as a substitute 

 for sulphur, under the name of Lycopod or vegetable brimstone. 

 The minute spores of Lycopodiwm clavatiim, in the form of a yellow 

 powder, are shaken out of the sporangia, and are used externally for 

 dusting excoriated surfaces, and putting in piU-boxes to prevent the 

 mutual adhesion of pills. Church has found Potassium Phosphate in 

 large quantity in the ash of Lycopodium giganteum. Two or three 

 species of Selaginella, as S. convoluta and involvens, coil up into a ball 

 during the dry season, and unroll during the wet season. They 

 have been called resurrection plants. 



Order 219. — Mtrsci, or Beyace^, the Moss Family. Plants 

 having a distinct axis of growth, often giving off branches or innova- 

 tions ; no vascular system. Leaves minute and imbricated (fig. 885 /), 

 entire, or serrated ; sometimes with condensed cells in the form of 

 ribs or nerves. Keproductive organs of two kinds : — 1. Antheridia 

 (figs. 402, p. 233 ; 494, p. 277), cylindrical or fusiform stalked bags, 

 containing minute cells with spermatozoids (fig. 402, 3, p. 233), and 

 mixed with empty jointed filaments or paraphyses (nta^af^eig, an off- 

 set). 2. Urn-shaped sporangia (figs. 887; 495, p. 277),enclosed at 

 first within a calyptra (yiaXMrga, a cover or veil), which is ultimately 

 carried up with them (fig. 886 c), leaving often a sheath (vaginula) 

 round the bottom of the fruit-stalk. These spore-cases (fig. 885) 

 are supported on a stalk or seta, which has leaves at its base, called 

 perichsetial leaves {'ti^, around, and %a;V^, flowing hair, foliage) ; on 

 removal of the calyptra, the theca is found to consist of a case with 

 an operculum or lid (flg. 887), which, when it falls off, shows the 

 mouth of the um either naked or crowned with a peristome (wsf', 

 around, and ero/j^a, mouth), consisting of one or more rows of teeth 

 (in number, four, or a multiple of four), distinct, or united in various 

 ways (fig. 887 p). In the centre of the theca is a columella (fig. 

 888 c), and the bag formed between it and the parietes of the theca 

 contains spherical cells called spores (fig. 888, s). In some cases the 

 operculum remains persistent, and the theca opens by four valves. At 

 the base of the theca there is occasionally a fleshy protuberance at 

 one side, called a struma, or a swelling of the seta, called an apophysis 

 (u'ffoipueig, excrescence), (fig. 888 a). The calyptra is sometimes split 

 on one side (dimidiate), at other times it is entire (fig. 886 c) or split 

 into short clefts all round its base (mitriform). Between the teeth of 



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