BRTOPRTTA. 



189 



cells extending from tlie leaves to the bundle in the stem. 

 It cannot be doubted, then, that the Mosses possess rudi- 

 mentary fibro-vascular bundles. As in liverworts, the tis- 

 sues of mosses develop from a single apical cell. Breathing- 

 pores resembling those of the higher plants occur on the 

 spore-fruits; they are not found upon the leaves or stems. 



395. Mosses, for the most part, grow upon moist earth 

 or rocks, or upon the sides of trees; 

 comparatively few are aquatic. 

 They range in size from less than a 

 millimetre to many centimetres in 

 length, the most common height 

 being from two to four centimetres. 

 They are all chlorophyll-bearing 

 plants, and are generally of a bright- 

 green color; occasionally, however, 

 they are whitish or brownish. 



396. The reproduction of mosses 

 is mainly sexual, but occasionally 

 buds are found resembling those of 

 the liverworts. The sexual organs 

 develop either upon the end of the 

 stem, within flower-like rosettes of 

 leaves, or in the axils of the leaves. 



The antherids are club-shaped or 

 globose trichomes (Fig. 105), whose 

 interior cells (sperm-cells) produce 

 antherozoids. The sperm-cells, when 

 mature, escape from the antherid 

 through a rent in its wall. Each sperm-cell contains one 

 spirally coiled antherozoid, which, when set free, swims by 

 means of its two long cilia (Fig. 105, c). 



Fio. 105.—^, an antherid of 

 a Moss ruptured, showing 

 the mass of sperm-cells, a — 

 magnified 350 times; b, a 

 sperm - cell, magnified SOO 

 times, showing antherozoid, 

 which at c is free. 



