144 



THE GREEN-HOUSE. 



that those which have done growing, and have ma- 

 tured their leaves, may be placed in situations much 

 less illuminated than the others. 



The habits of plants as to dropping their leaves 

 are different. Some part with the whole annually, 

 and at once, and leave the plant bare, as deciduous 

 plants ; others part only with a portion annually, and 

 retain a sufficiency to render them perpetually clothed, 

 as evergreens. The first suffer no injury from being 

 kept whilst in a naked state in a situation with little 

 or no light. Hence some green-house plants, as the 

 Fuchsia, Aloy^sia, &c., may be removed from the 

 stage in their resting-season, and placed under it, or 

 in any dark part of the house, or in a temperate shed 

 or cellar. 



Air (independently of its motion as wind) is es- 

 sential to every function of plants, from germination 

 to ripening the seeds. A free circulation of air is 

 essential to the flavouring of fruits, and in green- 

 houses to the carrying off of damp unwholesome va- 

 pours, or excess of moisture in the atmosphere, which, 

 when not accompanied by abundance of light and 

 heat, is apt to create a mouldiness on plants and the 

 surface of their pots, and encourage the growth of 

 mosses and fungi, which are doubly injurious to 

 plants, by impeding transpiration and imbibing their 

 nourishment. As from the moist state of the earth 

 in the pots, and the warm temperature of the green- 

 house compared with that of the open air during 

 winter, its atmosphere must then be powerfully 



