PLANT-HOUSES. 



339 



469 



cious to keep out the cold than any mats. Sometimes merely a bottomless 

 box of wood is used, like the wooden frame of the cold pits already described, 

 but only for one or 

 two lights. This box 

 is set on the ground, 

 and the frost is pre- 

 vented from pene- 

 trating through the 

 woodwork, by sur- 

 rounding it with 

 dead leaves, straw, 

 litter, or even earth. 

 Figs. 337. and 338. 

 show a cold pit of 

 somewhat larger di- 

 mensions, made with 

 a span roof in order 

 to give room for 

 camellias, and other 



