io6 THE BOOK OF NATURE STUDY 



moist, or by cultivating isolated leaves or bits of stem. Any 

 part of the plant rooting-hairs, leaves, stems can produce the 

 green threads and thus give rise to new plants. 



Some points not easily made out in Funaria can be seen in 

 larger mosses like the thyme thread-mosses (Mnium) and the 

 hair-mosses (Polytrichum). Of the former, which grow chiefly 

 in woods, beside streams and about the roots of trees, the com- 

 monest is Mnium Hornum (Fig. 22). It grows in tufts two or 

 three inches high, in which the individual plants are seldom 

 branched (except in the basal region which bears the rooting 

 hairs), and are dark green (except the young shoots, which are 

 pale green). The leaves are nearly J inch long, and are lance- 

 shaped with a pointed tip, a well-marked midrib, and a thickened 

 border bearing small teeth in pairs. 



The capsule is cylindrical, and at first hangs downwards on 

 the curved stalk, but when ripe and ready to shed the spores it 

 is raised and becomes nearly horizontal, pointing towards the 

 more strongly lighted side (as can be seen by setting young fruiting 

 plants near a window and changing their position now and then). 

 By carefully watching ripe fruits one can see that the separation 

 of the lid is due to a ring of tissue at its edge ; this ring comes 

 off as the ripe capsule dries, often becoming curled up in a single 

 piece, and the loosened lid then falls off. The peristome is double, 

 as in Funaria ; the outer peristome consists of sixteen tapering teeth 

 with free tips, the inner of a folded membrane bearing numerous 

 fine processes on its edge. The outer teeth and the membrane serve 

 to prevent the spores from falling out in a mass, but when the air 

 is dry the threads of the inner peristome move about and jerk 

 the spores out a few at a time. This can be seen by laying a 

 ripe capsule on white paper and breathing on it, watching what 

 happens as it is alternately moistened and dried. 



The sperm- and egg-pockets are easily found in Mnium, 

 especially the former, which are carried on special male shoots 

 whose lower leaves are small, while the upper ones spread out 

 like a flower. The centre of the male " flower " is a brown mass, 

 which, on being teased out in a drop of water on a slide, is seen 

 to consist of short-stalked cylindrical bodies, the sperm-pockets 

 (antheridia), mixed with numerous hairs. Slice a male " flower " 



