86 SECRETIONS. 



" The odour of plants," says Dr. Smith, " is un- 

 questionably of a resinous nature, a volatile essential 

 oil, and several phenomena attending it well deserve 

 our attentive consideration. Its general nature is evin- 

 ced by its ready union with spirits or oil, not with wa- 

 ter, yet the moisture of the atmosphere seems, in 

 many instances, powerfully to favour its diffusion. 

 This I apprehend to arise more from the favourable 

 action of such moisture upon the health and vigour of 

 the plant itself, thus occasionally promoting its odorous 

 secretions, than from the fitness of the atmosphere, so 

 circumstanced to convey them. Both causes, howev- 

 er, may operate. A number of flowers which have no 

 scent in the course of the day, smell powerfully in the 

 evening, whether the air be moist or dry, or whether 

 ihey happen to be exposed to it or not. This is the 

 property of some which Linnagus has elegantly called 

 Jlores tristes, melancholy flowers, belonging to various 

 tribes us discordant as possible, agreeing only in their 

 nocturnal fragrance, which is peculiar, very similar 

 and exquisitely delicious in all of them, and in the pale 

 yellowish, greenish, or brownish tint of their flowers. 

 The sweet smell of new hay, (sometimes termed the 

 gramineous flavour) is found not only in several Grass- 

 es, but in Woodruff, Mellilot, and other plants widely 

 different from each other in botanical characters, a- 

 well a* in colour and every particular except smell. 



Their odour has one peculiarity, that it is not at all 

 perceptible while the plants are growing, nor till they 

 begin to dry. It proceeds from their whole herbage, 

 and should seem to escape from the orifices of its con- 

 taining cells, only when the surrounding vessels, by 

 growing less turgid, withdraw their pressure from such 



