MOSSES. 



325 



cell now forms two rows of segments by partition-walls inclined alternately, and 

 these segments are next divided by radial vertical walls, followed by further 

 numerous transverse divisions. By this process the young sporogonium growing 

 at its apex is transformed into a multicellular body which is usually fusiform, the 

 lower end not participating in the growth in length. A swelling of this lower 

 end, such as usually occurs in Hepatic^, takes place also in Sphagnum and Archi- 

 dium. The apex of the sporogonium now becomes inactive, and beneath it the 

 capsule is formed from a spherical, ovoid, cylindrical, or frequently unsymmetrical 

 swelling which originates, in the typical IMosses, only after the elongation of the 

 fusiform or cylindrical sporogonium, and after the raising up of the calyptra. The 

 internal differentiation of this mass of tissue, at first homogeneous, forms the various 

 tissues which compose the capsule of ]\Iosses, and especially the mother-cells of the 

 spores which first of all become isolated and then divide each into four spores. The 

 contents of the mother-cell begin to divide into two, but this bipartition is usually 

 not completed, the division into four taking place at once. The preparation for the 

 formation of spores takes place simultaneously everywhere within the same capsule. 

 The ripe spores are roundish or cubical, surrounded by a thin finely granulated exo- 

 spore, which is of a yellowish, brownish, or purple colour. Besides protoplasm, 

 they contain chlorophyll and oil. In Archidium, where only sixteen are formed 

 in each capsule, they are about | mm. in size, in the highly developed Dawsonia 

 scarcely 75-J^ mm. (Schimper). . When kept dry the spores often retain their power 

 of germmation for a long time, but when moist they frequently germinate after a 

 few days, those of Sphagnum after two or three months. 



The time necessary for the formation of the sporogonium varies greatly in the 

 different species, but is usually very long in comparison with the small size of the 

 body concerned. The Pottieie blossom in summer, and ripen their spores in the 

 winter ; the Funariae are perennially in blossom, and have constantly sporogonia in 

 all stages of development, occupying for its completion probably 2 to 3 months ; 

 Phasciim cuspidatum developes in the autumn from its perennial underground proto- 

 nema, and ripens its spores in a few weeks before the winter. The bog Hypna, on 

 the other hand {H. giganteum, cordi/oh'um, cuspidatum, nitens, &c.), blossom in August 

 and September, and ripen their spores in June of the next year ; they often require 

 ten months for the development of their sporogonia. H. cupressiforme bears in 

 autumn at the same time flowers and ripe spores, and hence requires one year. 

 The same length of time is required by Philonotis, and by some species of Bryum 

 and some of Polytrichum which blossom in May and June \ 



Mosses may be distributed naturally into four parallel orders: — 



1. Sphagnaceae, 



2. Andreaeaceae, 



3. Phascaceae, 



4. Bryaceae (True Mosses). 



Of these the first includes a single genus, the second and third only a few ; the fourth all 

 the remaining extremely numerous genera. The first three groups recall, in many 

 respects, the Hepaticae ; even the series of true Mosses commences with some genera 



Klinggraff, Bot. Zeitg. i860, p. 344- 



