The Ecology of Calluna vulgaris. 73 
moment before the joint is made air-tight with hot paraffin wax, 
the air inside the cover C is maintained in a moist condition. 
Once planted and placed under suitable conditions, little 
attention is required. 
Text-fig. 2. Apparatus for growing sterilized seedlings in sand cultures. 
Lettering :—/, cotton wool plug ; c, glass cover ; s, shoulder filled with sterile 
sand ; r, rubber cork ; /. Massen filter candle. 
