(44) 



most by the use of a lens. In addition to these characters, 

 the capsule or the receptacle which bears the spores, or 

 reproductive bodies, usually splits into four valves when 

 full-grown and the spores themselves are accompanied by 

 spiral threads called elaters. The favorite habitat of 

 hepatics is wet places, and mountains continually steeped 

 in clouds yield a surprising variety of forms. Closely re- 

 lated to the hepatics, and commonly included with them, 

 is the group Anthocerotes; these plants may, however, be 

 distinguished by the presence of a central axis or column 

 (columella) in the capsule, and there are several other im- 

 portant structural differences in their tissues. 



The mosses (cases 41 to 48) follow the hepatics in order 

 of development and complexity; they differ from them, 

 however, in many respects. The stem and leaves have 

 more differentiated tissues, and the leaves usually have a 

 midvein. The moss capsule generally opens by a lid under 

 which there are commonly appendages to aid in scattering 

 the spores, which in this case are not accompanied by 

 spiral threads as they are in the hepatics. The mosses 

 fall into three primary groups: First the "peat-mosses" 

 {Sphagnum), which differ from the rest of the mosses in 

 the development of the tissue-structure of the capsule and 

 in the spores; they grow in swamps and other wet places, 

 and their accumulation forms peat. The "black mosses" 

 {Andreaea) differ from both of the other groups in the 

 valvular capsule; they grow on dry rocks. The true mosses 

 vary exceedingly in size and aspect. An examination of 

 the specimens in the exhibition cases will convey to the 

 mind a better idea of this group than may be gained from 

 a description. They grow under all kinds of conditions 

 from dry rocks to deep water. Many of the kinds grow on 

 almost any kind of rock, earth, or bark of trees, while 

 certain ones are more particular as to their habitat. Some 

 will thrive only on limestone, which they often gradually 

 disintegrate and partially preserve in the masses of closely 

 set plants as a calcareous tufa; other species prefer ground 



