IS$ SENSIBLE PERSPIKATION. 



fleshy roots, indeed have a singular power of resisting 

 drought, which hasakeady been explained p. 101. Suc- 

 culent plants, destined to inhabit sunny rocks, or sandy 

 deserts, imbibe with the greatest facility, and perspire 

 very sparingly. Evergreens are not generally very suc- 

 culent, but their cuticle appears to be constructed like 

 that of succulent plants, so as to allow of little evapora- 

 tion. The Cornelian Cherry, whose immense perspi- 

 ration we have recorded, p. 67 y has a thin dry leaf, ca- 

 pable of holding very little moisture. 



The nature of the liquor perspired has been already 

 noticed, p. 67. In hot weather it has been observed by 

 Hales, Du Hamel and Guettard to partake occasionally 

 of the peculiar scent of the plant that yields it, but in 

 general the odorous matter is of too oily a nature to be 

 combined with it. 



The sensible perspiration of plants is of various kinds. 

 When watery, it can be considered only as a condensa- 

 tion of their insensible evaporation, perhaps from some 

 sudden change in the atmosphere. Groves of Poplar 

 or Willow exhibit this phoenomenon, even in England, 

 in hot calm v/eather, Vv^hen drops of clear water trickle 

 from their leaves like a slight shovver of rain. Some- 

 times it is of a saccharine nature, as De la Hire observ- 

 ed in Orange trees ; Du Hamel Arb. v. 1. 150. It is 

 more glutinous in the Tiiia or Lime-tree, more resin- 

 ous in Poplars, as well as in Cistus creticus, from which 

 last the resin called Labdanu?n is collected, by beating 

 the shrub with leather thongs. See Tournefort's Voyage^ 

 29. In the Fraxinella, Dictamus albus, it is a highly 

 inflammable vapour, Ovid has made an elegant use of 



