MUSCINE^ 1.35 



filamentous structure, the prothallus or protoneme, on which the leafy 

 plant containing chlorophyll arises as a lateral shoot. The Muscinese 

 present, therefore, an illustration of the phenomenon of alternation ol 

 generations ; the sexual generation which intervenes between germina- 

 tion and impregnation, or oophyte, consisting of . the protoneme (when 

 present), the leafy (or thalloid) plant, together with the sexual organs : 

 the non-sexual generation intervening between impregnation and ger- 

 mination, or sporophyte, consisting of the sporogone only with its 

 spores. 



The Muscineae are divided into two well-marked families, the Muse. 

 or Mosses, and HepaticcB or Liverworts. In the Musci the immediate 

 result of the germination of the spore is always a protoneme consisting 

 of branched rows of green or colourless cells, and often growing for i 

 considerable time independently, even after it has produced leafy stem; 

 by lateral budding. The vegetative structure is always cormophytic 

 and consists of a filiform stem furnished with two, three, or four rows o 

 leaves, not exhibiting any distinct bilateral structure, and branching 

 monopodially, never dichotomously. The sporogone is only for a time 

 enclosed in the calypter, which is usually eventually ruptured below, the 

 lower portion developing into the vagine, while the upper part is elevatec 

 above the apex of the sporogone .in the form of a cap. The spore 

 mother-cells are produced from one or more special layers of tissue 

 ;within the sporange, the arckespore, while the axial mass develops inte 

 a solid columel. The uppermost portion of the wall of the sporange 

 forms a lid or opercule, which usually becomes detached from the lowe 

 portion, to which the term theca or sporange specially belongs, to allov 

 the escape of the spores. The outermost layer of cells of the wall o 

 the sporange is more or less completely differentiated into an epiderm 

 which is frequently penetrated by stomates. When the opercule i 

 removed, the rim of the sporange is either quite smooth, when it i 

 te.n-a&d. gymnostomous, or the edge is furnished with delicate hair-liki 

 appendages, constituting the peristome, arranged in a single row or fre 

 quently in two, when they are called respectively teeth and cilia, th 

 former constituting the outer, the latter the inner row. The number c 

 both teeth and cilia is always a multiple of four, or more correctly speak 

 ing, a ' power ' of two. In the Hepaticae the protoneme is either scantil 

 developed or is altogether suppressed. The rest of the sexual generatioi 

 consists either, of a flat dichotomously branched thallus or thalloid stem 

 or of a slender stalk furnished with two or three rows of leaves. In th 

 division into Foliose and Thalloid or Frondose forms, the Hepatics 

 therefore present the transition from Cormophytes to Thallophytes. Th 

 .mode of growth is always distinctly, bilateral ; the thalloid forms clin^ 



