28 HISTORY OF BRITISH FERNS. 



the particles ; the clean white sand, called Reigate sand, is 

 that most generally employed. 



The supply of water to Ferns under artificial conditions 

 is a very essential matter ; they must never lack moisture, 

 or their fragile texture shrinks as before a burning blast ; 

 nor, with few exceptions, must the soil about them be kept 

 continually wet with stagnant water; indeed, stagnant 

 water is in all cases to be avoided. 



