264 



of region of vines, region of laurels, region of 

 pines, region of the ratama, and region ofgrasses. 

 These zones are arranged in stages, one above 

 the other, and occupy, on the steep declivity of 

 the Peak, a perpendicular height of 1750 toises ; 

 while fifteen degrees farther north, on the Py- 

 renees, the snows already descend to thirteen or 

 fourteen hundred toises of absolute elevation. 

 If the plants of TenerifFe do not reach the sum- 

 mit of the volcano, ijb is not because the perpetual 

 snows *, and the cold of the surrounding atmo- 



the Canaries from the manuscript notes of Mr. Broussonet. 

 When I published my first " Essay on the Geography of the 

 Equinoctial Plants of the New World," I begged this distin- 

 guished naturalist, who had long resided at Mogadore, in the 

 empire of Morocco, and at Santa Cruz, in TenerifFe, to com- 

 municate to me his ideas relative to the geographical distribu- 

 tion of plants in those countries. He yielded to my entreaty 

 with that complaisance and urbanity, which he constantly ex- 

 ercised in his communications with learned foreigners. 



* Though the Peak of TenerifFe is covered with snow dur- 

 ing the winter months only, it is nevertheless possible, that the 

 volcano reaches the limit of the perpetual snows correspond- 

 ing to it's latitude, and that the total absence of the snows in 

 summer is owing to the isolated situation of the mountain in 

 the midst of the seas, to the frequency of the ascending hot 

 winds, or the elevated temperature of the ashes of the Piton 

 but we are unable to solve these doubts, in the present state 

 of our knowledge. From the parallel of the mountain of 

 Mexico to that of the Pyrenees and the Alps, between the 

 20th and the 45th degrees, the curve of the perpetual snows 

 has not been determined by any direct measure 3 and as an 



