134 ROCK GARDENS 



— and then leave them for a day or more 

 before using. This will destroy most of the 

 seeds and spores of weeds and kill all worms 

 and insects, which is no little advantage. 

 For subsequent waterings use nothing but 

 boiled water. If neither of these plans is 

 adopted, the only course left is to pick off 

 every particle of the Marchantia as soon 

 as it appears, which is by no means easy 

 to do without disturbing the seed or young 

 plants, and will entail considerable labour 

 if there are a large number of pots to look 

 after. 



It is most essential to keep the soil at 

 the proper degree of moisture, which is not 

 at all easy to accomplish, and will require 

 constant attention. Nothing proves more 

 fatal to seeds than to allow the soil to 

 become dust-dry ; while, on the other hand, 

 if it is kept too moist, the seeds are very liable 

 to rot away. Above all, avoid alternate 

 conditions of wet and dry. For, germina- 

 tion having once commenced, if the soil is 

 subsequently allowed to dry up, the seeds 

 will be irrevocably destroyed. 



