before the Botanical Congress in London. 233 
to the wish of the observer?” My question passed unnotice 
in a voluminous work where, in truth, it was but an accessory. 
I renew it now in the presence of an assembly admirably quali- 
fied to solve it. I should like, were it possible, to have a green- 
house placed in some large horticultural establishment or botanic 
garden, under the direction of some ingenious and accurate 
physiologist, and adapted to experiments on vegetable physiol- 
ogy; and this is, within a little, my idea of such a construc- 
tion ;— 
The building should be sheltered from all external variations 
of temperature; to effect which I imagine it shou e ina 
great measure below the level of the ground. I would have it 
built of thick brickwork, in the form of a vault. The upper 
convexity, which would rise above the ground, should have two 
& 
fixed degree of temperature could be obtained as in a cellar. 
The vaulted building should have an underground communica- 
ge cl a series of successive doors, 
The temperature should be regulated by metallic conductors, 
heated or cooled at a distance. Engineers have already devised 
ratus when necessary. 
Obviously, with a hothouse thus constructed, the growth of 
plants could be followed from their germination to the ripening 
of their seeds, under the influence of a temperature and an 
amount of light perfectly definite in intensity. It could then be 
_ ascertained how heat acts during the successive phases from 
4 G . . 5 ‘ . 
= thet. psi yo cased. 3 roe tar exhibited at Chiswick in 1837, 
figured in the “ Flore dot Beeston 4 Jardins,” vol. xii, Miscell. p. 184. aa 
