A third plague of the wanderer in the Puna is the _Veta_, which is occasioned by the great rarefaction of the air. Its first symptoms, which generally appear at an elevation of 12,000 feet, consist in giddiness, buzzing in the ear, headache, and nausea. Their intensity increases with the elevation, and is aggravated by a lassitude, which augments to such a degree as to render walking impossible, by a great difficulty of respiration, and violent palpitation of the heart. Absolute rest mitigates these symptoms; but on continuing the journey they reappear with increased violence, and are then frequently accompanied by fainting and vomiting. The capillary vessels of the eye, nose, and lips burst, and emit drops of blood. The same phenomenon appears also in the mucous membrane of the respiratory and digestive organs; so that blood-spitting and bloody diarrhœa frequently accompany the Veta, and are sometimes so violent as to cause death. The influence of diminished atmospheric pressure likewise shows itself in the horses that are unaccustomed to mountain travelling. They begin to pace more slowly, frequently stand still, tremble all over, and fall upon the ground. If not allowed to rest, they invariably die. By way of a restorative their nostrils are slit open, which seems to be of use by allowing a greater influx of air. As the dry sand of the rainless coast prevents the putrefaction of animal substances which are buried in it, the power of the dry Puna-winds in a like manner arrests the progress of decomposition. Under their influence, a dead mule changes in a few days into a mummy, so that even the entrails do not exhibit the least sign of putrefaction. It may easily be imagined that, under these circumstances, vegetation can only appear in stunted proportions, and indeed the Puna presents the monotonous aspect of a northern steppe, its whole surface being covered with dun and meagre herbage, which at all times gives it an autumnal or even wintry aspect. A few arid compositæ and yellow echinocacti are quite unable to relieve the dreary landscape; and even the large-flowered calceolarias, the blue gentians, the sweet-smelling verbenas, and many other Alpine plants, the usual ornaments of the higher mountain regions, are here almost suffocated by the dense grasses. But rarely the eye meets with a solitary queñua tree (_Polylepis racemosa_) of crippled growth, or with large spaces covered with red-brown ratania shrubs, which are carefully collected for fuel, or for roofing the wretched huts of the scanty population of these desolate highlands.