| OCR Text |
Show 152 STEPPES AND DESERTS. lidos) j or provided with leaves (Pereskire ). Many extend high up the sides of the mountains. Near the foot of the Chimborazo, in the elevated sandy plain around Riobamba, I have found a new kind of Pitahaya, the Cactus sepium1 even at a height of 10,000 (10,6GO Eng.) feet. (Humboldt, Bonpland, and Kunth, Synopsis Plantarum requinoct. Orbis novi, t. iii. p. 370.) ( 88) P· 37.-(1 Tlte scene in the Steppe is suddenly changed." I have endeavored to depict the coming in of the rainy season, and the signs by which it is announced. The usual deep dark azure of the sky in the tropics arises from the more complete solution of the vapor contained in the atmosphere. The cyanometer indicates a paler blue as soon as the vapors begin to be precipitated. The dark spot or patch in the constellation of the Southern Cross gt·adually becomes indistinct as the transparepcy of the atmosphere diminishes, and this alteration announces the near approach of rain. The brightness of the l\fagellanic clouds (Nubecula major and minor), gradually vanishes in a similar manner. The fixed stars, which before shone like planets with a steady, tranquil, and not trembling light, now scintillate even in the zenith, where the vapors are least. (Sec Arago, in my Relation hist. t. i. p. 623.) All these appearances are the results of the increased quantity of vapor diffused in the atmosphere. (39) p. 38.-((Awalcened frorn a torpid state by the first fall of 1·ain." Extreme dryness produces in plants and animals the same phenomena as docs the withdrawal of the stimulus of heat. 1\Iany tropical trees and plants shed their leaves during the dry season. The crocodiles and other amphibious animals hide themselves in the mud, where they lie apparently dead, like animals in a state of hybernation or plunged into winter sleep by cold. (See my Relation historique, t. ii. pp. 192 and 626.) ( 10 ) p. 38.-11 The aspect of a vast inlancl sea." Nowhere are these inundations more extensive than in the network of rivers formed by the A pure, the Arachuna, Pajara, Arauca, |
