GREENHOUSES. 187 



and as improvements in form, habit, and colour are so rapidly 

 being effected by cross-breeding and hybridising — it will be 

 evident to all that no good could result from swelling these 

 pages with descriptions of varieties which may be superseded 

 in the course of some ten or twelve months. 



GEEENHOUSES. 



E here give a transverse section and ground plan of 

 a house suited for the cultivation of plants from 

 the Cape of Good Hope, New Holland, New 

 Zealand, Chili, or from most of the temperate regions of 

 the globe, being such as are usually denominated Green- 

 house Plants. The dimensions and general form of the 

 house are the same as in the structure recommended for 

 Stove Plants, but with this difference — that in the Green- 

 house the side lights are all made to open, and the lantern is 

 not used, but the upper sashes of the roof slide up and down 

 in the ordinary way. The underground system of ventilation 

 should be applied to this structure as well as to the Stove, 

 as it affords means of maintaining a pure and healthy 

 atmosphere in the interior without injury to the plants, 

 even in the most severe weather. Fresh air. is most essen- 

 tial to the well-being of Greenhouse Plants, but cold draughts 

 must be avoided, for nothing is more injurious to plants of 

 any kind. .Indeed, such conditions often result in their 

 speedy death. This must be carefully attended to in giving 

 air to plant houses. 



