THE SCOURING-RUSHES. 23 



urged on by those behind. As each fat little spore 

 reaches the open, it unfolds its elaters like four tiny wings 

 and quickly sails out of the field. As long as the mois- 

 ture in the tissues is evaporating they continue to come. 

 To change the scene, one has only to dip his specimen 

 into water or to breathe upon it. At once every elater is 

 coiled. Even those spores just balanced on tip-toe as it 

 were, ready for flight, decide to remain, and all seem 

 trying to shrink into the smallest space possible. The 

 change is due to the hygroscopic nature of the elaters, 

 which coil in the presence of moisture. This character- 

 istic ensures that the spores shall not set out on their 

 travels until a fair day comes and the sailing is good, and 

 also prevents the elaters from being folded again and the 

 spores dropped until a moist interval, suitable for ger- 

 mination, occurs. 



The rough and flinty exterior of this species makes it 

 useful for scouring and polishing. It was once of prime 

 importance in domestic affairs, being used for cleaning 

 pots, pans, floors, and other woodwork. Cabinet-makers 

 and others also found many uses for it, but with the 

 advent of scouring-soaps and sandpaper it has gradually 

 fallen into disuse. In our own country, a few Indians 

 on the borders of civilization still use it for polishing 

 the shafts of arrows and similar work. It is said to be 

 occasionally used in the Old World also at the present 

 day. 



The names of " scouring-rush," " scrub-grass," " shave- 

 grass/' " polishing-rush," and "gunbright " all allude to 

 its use in polishing, while the term " naked horsetail" 

 has reference to the branchless nature of the stems. In 

 some sections the slender jointed stems have suggested the 

 name of ''bamboo." "Joint-rush" and "joint-grass" 



