no 



THE BOOK OF NATURE STUDY 



leaving narrow spaces through which the spores escape, the 

 whole peristome becoming shorter (Fig. 24). When moistened 

 the peristome expands again and the threads are tightly rolled 



FIG. 24. Peristomes of Screw Mosses. 



up. In some kinds the threads start from the edge of the capsule 

 mouth (where the lid fell off), but in others there is a tube or collar 

 below the teeth, so that the escape of the spores in dry weather 

 is still further limited. 



