168 



temperate, and stagnant air. If they sometimes 

 descend toward the coast, it is only under co- 

 ver of a thick shade. The old trunks of the 

 cyathea, and the meniscium, are covered with 

 a carbonaceous powder, which, probably de- 

 prived of hydrogen, has a metallic lustre like 

 the graphite. No other plant presents us with 

 this phenomenon ; for the trunks of the dico- 

 tyledons, in spite of the heat of the climate, and 

 the intensity of the light, are less burnt under 

 the tropics than in the temperate zone. It may 

 be said, that the trunks of the ferns, which, like 

 the monocotyledons, are enlarged by the re- 

 mains of the petiolae, decay from the circumfe- 

 rence toward the centre, and that, deprived of 

 the cortical organs, through which the elabo- 

 rated juices descend toward the roots, they are 

 burnt more easily by the action of the oxygen 

 of the atmosphere. I brought to Europe some 

 of those powders of metallic lustre, taken from 

 very old trunks of meniscium and aspidium. 



As we descended the mountain of Santa Ma- 

 ria, we perceived the arborescent ferns dimi- 

 nish, and the number of palm-trees increase. 

 The beautiful butterflies with large wings, the 

 nymphales, which fly at a prodigious height, 

 became more common. Every thing announc- 

 ed that we drew near the coast a and approach- 

 ed a zone, the mean temperature of which was 

 from 28 to 30 cent, degrees. 



