MOSSES. 



MOSSES. 



Many of them have one or more distinct 

 nervules, composed of elongated cells, often 

 not reaching- the apex of the leaf. 



The leaves often differ on different parts 

 of the stem ; and we hence have radical, 

 cauline, and perichcetial or involucral leaves, 

 the last ordinarily forming a kind of rosette, 

 in the midst of which the reproductive or- 

 gans are produced. SCHISTOSTEGA exhibits 

 two forms of stems, with two kinds of folia- 

 ceous structure : the stems which terminate 

 in a sporange have leaves only at the upper 

 part, and these arranged in eight rows 

 standing crosswise on the stem, like ordi- 

 nary leaves ; the barren stems have two 

 rows of leaflets arranged in one plane on the 

 stem, like the leaflets of a compound leaf 

 (such as that of the Acacias) of Flowering 

 plants. The stem-leaves of many genera 

 exhibit wing-like structures, hair-like ap- 

 pendages, or peculiar forms of curvature 

 (tigs. 242-246, FISSIDENS); others, like 



Fig. 463. 



Fig. 464. 



Barbula chloronotus. 

 Fig. 463. Leaf with cellular filaments at the tip. Magn. 



30 diams. 

 Fig. 464. Leaf with cellular filaments crowded on the 



midrib, with an awn-like prolongation. 



Magn. 20 diams. 



certain Barlults (figs. 463-466), have col- 

 lections of cellular filaments on the upper- 

 side. 



The outer leaves surrounding the repro- 

 ductive organs are called perichcetial, and 

 sometimes they form the only envelopes ; 

 sometimes, however, a few small leaves, 

 differing very much from the above, form 

 the immediate envelopes of the archegones ; 

 and these perigonial leaves, forming the 

 perigone, are developed after the reproduc- 

 tive organs themselves (as is the case also 



with the perigone of the Hepaticae). The 

 perigonial leaves either overlap and cover-in 

 the reproductive organs, or they are keeled 

 at the base and turned back above, so as to 

 expose the organs of reproduction (PoLY- 

 TRICHUM). 



The Mosses have no roots, their function 



Fig. 466. 



Barbula chloronotus. 



Fig. 465. Cross-section of 463. Magn. 50 diams. 

 Fig. 466. Cross-section of 464. Magn. 50 diams. 



being performed by root-hairs or rhizoids, 

 usually brown. 



The young reproductive organs consist 

 of antheridia, and archegonia or pistillidia, 

 which are found either together (fig. 467), 



Fig. 467. 



Fig. 468. 



Bryum nutans. 

 Fig. 467. Inflorescence of antheridia and archegonia. 



Magn. 25 diams. 

 Fig. 468. Spermatozoids from antheridia. Magn. 600 



diams., the cilia omitted. 



or on different parts of the same plant, or on 

 different individuals of the same species. 



Fig. 469. 



Mnium arcticum. 



Antheridial inflorescence. 



Magnified 25 diameters. 



To these structures the term inflorescence is 

 applied. The antheridia occur either with 

 the archegones in one perigone (fig. 467) or 



