This unequal voracity of the insects in different places, this various intensity of poison in the same species, are very remarkable, but similar phenomena are met with in the classes of the large animals. In Angostura the crocodile attacks man, while in New Barcelona people bathe in his presence without fear. The jaguars on the isthmus of Panama are cowardly when compared with those of the Upper Orinoco; and the Indians know very well that the monkeys from one part of the country can easily be tamed, while individuals of the same species caught elsewhere will rather die of hunger than submit to captivity. Whoever has sojourned in a mosquito land knows that there is no radical remedy against them. The Indians who besmear their body with arnatto or turtle fat, slap every moment with their flat hands on their shoulders, back, and legs as often as if they were not painted at all. On the banks of the Amazons the people use cow-dung burnt at their doors, to keep away the praya or plague, as they very justly term the mosquitoes. In the evening every house and cottage has its pan of dung smouldering in the verandah and emitting rather an agreeable odour--but where the insects are very numerous and bloodthirsty this fumigation also is of no avail. Not content with a passing attack, a South American gadfly (_Œstrus hominis_) deposits its eggs under the human skin, where the larvæ continue for six months. If disturbed, they penetrate deeper, and produce troublesome ulcers, which sometimes even prove fatal. Thus, in tropical America, we find the same insect tribe which plagues our oxen and horses, and reduces the northern reindeer to desperation, settle on man himself, and render even the lord of creation subject to its power. The Chegoe, Pique, or Jigger of the West Indies (_Pulex penetrans_) is another great torment of the hot countries of America.