308 FEENS : BRITISH AND POEEIGN. 



species of JDavallia, and a few otters. Their rhizomes 

 remain perfectly naked during the winter, and seem 

 to be constituted for a season of dry rest. 



These obversations are sufficient to show how 

 certain species will grow under the most opposite 

 conditions, and that a knowledge of them materially 

 assists our efforts of cultivation, which I shall pro- 

 ceed to treat of under two heads, — special and 

 natural. 



n. Speciai. OB Pot CuiTrvATioN. 



WITH the exception of those species sufficiently 

 hardy to bear the cold of this climate, the 

 whole family of Ferns can be artificially and most 

 luxuriantly grown, under but two different scales of 

 temperature, and with as little difference in other 

 respects. There can be no better instance than that 

 afforded by the immense collection now at Kew,* where, 

 in tiie Tropical Fern-house, a great many species from 

 various climates are placed under an average tempera- 

 ture of 60° to 70°. In this housef are species from 

 nearly aU the tropical and sub-tropical countries 

 of the world, and, being in one compartment, they 

 are all alike subject to the same amount of atmo- 

 spheric moisture as of heat. However, in respect 

 to moisture supplied to their roots, the amount 

 is varied according to the nature and require- 

 ments of the plant. The same remarks apply to 

 the Temperate House, of course with a reduction 



* May 1864. t Length 130 feet, width 34 feet. 



