USE OF THE COLD FRAME AND THE HOTBED 309 



of boards nailed together to form a rectangle. The frame 

 is simply a box without a bottom, set into the ground. 

 Prepare the soil in this box with special care, using manure, 



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The relation between green plants and animals. 



and breaking the soil up into fine particles. Seeds planted 

 under glass will grow rapidly because of the heat which 

 is retained by it, and if the frames are covered up with 



Cold frame. 



thick cloths or blankets at night, plants may begin to 

 grow two months earlier in the spring and continue two 

 months later in the fall. The hotbed is a deeper box hav- 



