134 On the Heat in Forcing-houses. 



But the effect of no two operations can be more different : 

 in the one, the plant is suddenly chilled by cold water, and 

 subsequently kept cool by the evaporation of the water during 

 the night: in the other, the steam is precipitated upon 

 the leaves and branches of the trees, to which it necessarily 

 communicates much heat. The former operation nearly 

 resembles that of the shower-bath, sometimes used in this 

 country, in which the patient is suddenly chilled by a heavy 

 shower of cold water ; the other resembles the hot steam - 

 bath of Russia, in which he is violently heated ; and if the 

 gardener were to try each of these processes upon himself, 

 during a single night, I suspect he would arise in the fol- 

 lowing mornings with very different feelings, unless he were 

 blest with much peculiar hardness of constitution. It is true, 

 that plants do not appear to possess sensation in the ordinary 

 sense of that term, as it is applied to animals ; but nature, 

 in forming its whole organic creation, seems to have pro- 

 ceeded so much by substitutions and additions, that simple 

 sensation, in its strict and limited sense, abstracted from all 

 powers of perception, may not improbably be as widely 

 diffused as organization itself ; and animal and vegetable life 

 may be, in consequence, susceptible of similar injuries from 

 similar external causes. The influence of hot and damp air 

 upon both, is greatly more powerful than that of dry air of 

 the same temperature. In the experiments, of which Sir 

 Charles Blag den has given an account in the Philoso- 

 phical Transactions of 1775, he, with Sir Joseph Banks and 

 others, sustained without injury a temperature of 260 degrees 

 in dry air ; but they found damp air, at half that tempera- 



