At a very short distance from Lima, the traveller, proceeding eastward, gets a foretaste of the difficulties and inconveniences in reserve for him. Whilst riding, through the vale of Surco, or through some other of the valleys leading from the coast to the mountains, he perceives a fountain by the road side, and pauses to refresh his tired mule. Scarcely is his intention manifest, when he is startled by a cry from his guide, or from a passing Indian--"_Cuidado! Es agua de verruga!_" In these valleys reigns a terrible disease called the _verrugas_, attributed by the natives to the water of certain springs, and for which all Dr Tschudi's investigations were insufficient to discover another cause. Fever, pains in the bones, and loss of blood from cutaneous eruptions, are the leading symptoms of this malady, which is frequently of long duration, and sometimes terminates fatally. It seizes the Indians and lighter castes in preference to the white men and negroes, and no specific has yet been discovered for its cure. Mules and horses are also subject to its attacks. In no country, it would appear from Dr Tschudi's evidence, are there so many strange and unaccountable maladies as in Peru. Nearly every valley has its peculiar disease, extending over a district of a few square miles, and unknown beyond its limits. To most of them it has hitherto been impossible to assign a cause. Their origin must probably be sought in certain vegetable influences, or in those of the vast variety of minerals which the soil of Peru contains.