THE GEOGItArHY OF PLANTS. 365 



hundred and fifty species of melastomacese, "which we 

 collected during the course of our expeditions, and which 

 form one of the most beautiful ornaments of tropical 

 vegetation. M. Bonpland has added the plants of the 

 same family, which, among many other rich stores of 

 natural history, M. Kichard collected in his interesting 

 expedition to the Antilles and French Guiana, and the 

 descriptions of which he has communicated to us. 



" IV. Essay on the geography of plants, accompanied by 

 a physical table of the equinoctial regions, founded on mea- 

 sures taken from the tenth degree of northern to the tenth 

 degree of southern latitude. I have endeavoured to collect 

 in one point of view the whole of the physical pheno- 

 mena of that part of the New Continent comprised 

 within the limits of the torrid zone from the level of the 

 Pacific to the highest summit of the Andes ; namely, 

 the vegetation, the animals, the geological relations, the 

 cultivation of the soil, the temperature of the air, the 

 limit of perpetual snow, the chemical constitution of the 

 atmosphere, its electrical intensity, its barometrical pres- 

 sure, the decrement of gravitation, the intensity of the 

 azure colour of the sky, the diminution of light during 

 its passage through the successive strata of the air, the 

 horizontal refractions, and the heat of boiling- water at 

 different heights. Fourteen scales, disposed side by side 

 with a profile of the Andes, indicate the modifications to 

 which these phenomena are subject from the influence of 

 the elevation of the soil above the level of the sea. Each 

 group of plants is placed at the height which nature has 

 assigned to it, and we may follow the prodigious variety 

 of their forms from the region of the palms and arbores- 

 cent ferns to those of the johannesia (chuquiraga, Juss.), 



