of the Painted Corolla. 241 
Thus does it expand the blossom in virtue of the absorption of 
heat *■ from the sunbeam, and as it loses part of its acquired 
temperature by radiation toward the afternoon and evening, it 
will slowly close by the contraction of the fibres, the necessary 
consequence of decreased temperature. There may be instan- 
ces which seem counter to this deduction, such as the “ night- 
blowing cereusf the 66 marvel of Peru ,” &c. These plants, 
however, are not indigenous to Britain. The loss sustained by 
radiation on the part of the corolla, will reach its zero , when 
it amounts to that of the ambient air. The flower has now 
locked up its petals, and lower it cannot fall, though the tem- 
perature of the ambient air may continue to decline. 
The Nymphaa, and its congener the sacred Lotus of the 
Ganges and the Nile, gradually shut their flowers as the even- 
ing advances, and finally plunge beneath the wave, — a medium 
of uniform temperature, and where loss by radiation is un- 
known. 
I wish it to be distinctly understood, that I have been led to 
the opinion now presumed, in virtue of a very extensive series 
of experiments ( many hundreds ), on the temperature of the 
coloured corolla at different periods of the day, &c. To detail 
these would occupy some pages ,• but an example may be 
given. The ball of a delicate thermometer was, in such cases, 
either placed on the expanded polypetalous disc, or introduced 
inf;© the monopetalous bell, tube, &c. 
On the shelf of a greenhouse stage, Calla Mthiopica , 55° Fahr.; 
Rosa odor a , 56° Fahr.; Amaryllis Johnsoniana , 57° Fahr. : out 
of doors, air, 54.5, Cor chorus Japonica , 56°; double red 
Anemone , 57.5 Q Fahr. Air, 62° Fahr.; Beilis perennis, 61° 5'. 
In another experiment, air, 63° Fahr., Carduus , 64.5 ; Cam- 
panula^ 64°. And, Air , 58° Fahr. Centaurea montana , 59°; 
Leontodon Taraxacum , 60.5° ■)*. 
* Many an anxious visit to the Cactus grandiflorus has been disappointed ; 
but the Curator of the Botanic Garden at Hull informs me, that the corolla expands 
instantly , and with a species of elastic force, on bringing a chaffer of ignited coals 
near it. 
So have I found a gradually declining temperature in flowers toward even- 
ing ; the red coloured corolla being lower than the yellow , the blue still less, and 
the white not sensibly varied. 
VOL. IX. NO. 18. OCT. 1823. Q 
