34 



The Natukalist. 



the fruit, the month of the urn is seen to be closed by a lid, often 

 exactly the shape of the lid of a teapot, sometimes long and conical. 

 Under the lid the mouth of the nrn is in most mosses surrounded by 

 one or two rows of teeth, in number either 4 or some multiple of 4 

 by 2 — as 8, 16, 32, or 64. They vary very much in shape in different 

 mosses, but are always brightly coloured, and form beautiful objects. 

 They are highly hygroscopic, and exhibit remarkable movements with 

 varying degrees of humidity or dryness, as when breathed upon, and 

 at each movement a little cloud of spores is jerked into the air. 

 When the spores germinate they develop into a green conferva-like 

 thread, which soon produces stem and leaves, and then perishes. 



It is to be noticed that the product of the fertilized germ cell in 

 mosses is not what from the analogy of higher plants we should have 

 expected, a single spore, but a capsule containing many spores. 

 Hence it is considered by Hofmeister and other botanists that there 

 is an " alternation of generations " in mosses like that of ferns, the 

 duration of the two stages being inverted — the persistent sexual stage 

 of the moss corresponding to the prothallus, and the fruit- stalk and 

 capsule of the moss corresponding to the non-sexual perennial fern. 

 Besides the true spores mosses have several other means of propaga- 

 tion ; some have creeping rhizomes and send up suckers, the stems 

 of many send out rootlets and take root readily if broken off, others 

 again bear minute green bulbs on the stem or leaves, which fall off 

 and develop into young plants. So efficient are these supplemental 

 means of propagation, that many mosses which are common and 

 abundant are rarely or never found in fruit. 



Hepatic^ may be divided into scale mosses and liverworts ; the 

 latter have no distinct stem and leaves, the former have. The leaves 

 of scale-mosses have never any midrib, they are placed nearly in the 

 same plane as the stem, and inserted by a broad base, like the main- 

 sail is attached to a mast. They are often of singularly complicated 

 shapes, and furnished with stipules underneath. The fruit differs 

 from that of mosses in several respects ; as the stalk elongates, the 

 capsule bursts through the apex of the calyptra, which remains as a 

 sheath surrounding the base of the stalk, generally enclosed in a 

 calyx. The capsule has no lid nor peristome, but contains mingled 

 with the spores spiral elastic threads ; when ripe it splits into four 

 valves, and the spiral springs elongating, scatter the spores like a 

 pea is shot out of a child's toy-gun. In the genius Riccia, which 

 forms the link with the lichens, the spore-case is imbedded in the 

 frondj it does not burst, and contains no elaters. 



