217 



the night (in consequence of their being no fire), whilst at mid- 

 day it is frequently as high as 130°. This high temperature, how- 

 ever, does not often occur, as the house is shaded by a blind. 

 Circulation of the atmosphere is effectually secured by means of that 

 beneficent law which compels the diffusion of the various gases which, 

 either in a course of nature or as the result of various chemical ope- 

 rations, are continually being generated on the surface of the earth. 

 By virtue of this law, the moment any gas is formed in the house, 

 differing ii'om the atmosphere without, diffusion immediately takes 

 place ; and that uniformity of its component parts, which philoso- 

 phers have ascertained to be the case in air examined from every 

 portion of the earth's surface, is the result. Open exposure to air is 

 very seldom required with the majority of plants, whether natives of 

 cold or of hot regions, if their wants are duly supplied. Oxalis Ace- 

 tosella, Dentaria bulbifera, Primula vulgaris, Convallaria multiflora, 

 Cleodendron fragrans, Canna indica, Strelitzia Reginre, Begonias and 

 hosts of other plants, have flowered with me in closed cases for many 

 successive years ! and many fruits, particularly those of tropical 

 regions, ripen well. The fact is, that in these cases we are enabled 

 to include all the agents which can contribute to the well-being of 

 the plants, and exclude those which produce deleterious effects. 



" I cannot conclude without suggesting the adoption of this plan 

 in the general cultivation of plants. Where a large number of spe- 

 cies is required to be grown, a series of houses might contain repre- 

 sentations of various regions of the earth, fitted up to meet the wants 

 of the characteristic flora of each region, and forming most beautiful 

 tableaux vivans of the aspects of the vegetable kingdom. Thus, from 

 our miniature tropical forest we might pass to the sandy flats of the 

 Cape of Good Hope, with its bulbs, mesembryanthemums and heaths ; 

 and thence to New Holland, with its Epacrids and beautiful Legumi- 

 nosae, &c. ; and if sufficient elevation could be obtained, Teneriffe 

 might have a place in this grand exhibition, displaying its dragon 

 trees, laurel forests, columnar Euphorbiaceae, Cacti, &c., &c. Each 

 particular country might be thus represented. The Crystal Palace 

 might well be appropriated to such a design, which would, I think, 

 be quite as interesting as the purpose for which it was erected." 



' The Ash of Armeria maritima.' 



' New and Rare Plants,' giving many particulars of their appear- 

 ance and history. 



' Erica Leeana, var. viridis^ a description and excellent figure of a 

 well-known but rarely-cultivated plant. 



Vol. IV. 2 f 



